Nova (1974–…): Season 28, Episode 17 - Life's Greatest Miracle - full transcript
People do all sorts of things
to get attention.
And why?
It may be the last thing
on his mind
but this man's body
is working toward this.
Whether we're thinking
about it or not
our bodies want to make babies.
And our bodies
are very good at it.
Around the world, about 365,000
new babies get made every day.
But as ordinary as it seems
creating a new human being
is no simple feat.
Just think of it.
No matter who you are, once upon
a time, you looked like this.
From a single cell,
you built a body
that has 100 trillion cells.
You made hundreds
of different kinds of tissues
and dozens of organs
including a brain that allows
you to do remarkable things.
How did you do it?
Today, we can look closer
than ever before...
Into the womb...
into a cell...
into the essence of life itself.
Not only can we see
what's happening
but now, we're beginning
to see how it happens...
The forces that build
the embryo;
the molecules that drive
this remarkable change.
We're uncovering
the most intimate details
of how life is created...
The secrets behind
"Life's Greatest Miracle."
Captioning sponsored
by PARK FOUNDATION
NORTHWESTERN MUTUAL FOUNDATION,
SPRINT PCS
THE CORPORATION
FOR PUBLIC BROADCASTING
Major funding for NOVA is
provided by the Park Foundation
dedicated to education
and quality television.
This program is funded in part
by the Northwestern
Mutual Foundation.
Some people already know
Northwestern Mutual
can help plan
for your children's education.
Are you there yet?
Science.
It's given us the framework
to help make wireless
communications clear.
Sprint PCS is proud
to support NOVA.
And by contributions
to your PBS station from:
You might think all the people
on this beach
are just working
on their suntans.
But beneath all that sunscreen,
under the skin
there's a frenzy of activity.
Without even thinking about it
almost all the adults here
are busy
trying to reproduce.
They can't help themselves.
The urge to procreate
is a fundamental part of life
not just for us,
but for all life.
Why is this urge so universal?
At least some blame
can probably go to this...
DNA, the molecule
that carries our genes;
the chemical instructions
for building our bodies
and keeping us alive
all wrapped up
in a tiny winding staircase.
DNA has run the show for more
than four billion years
for one main reason:
It's very good
at making copies of itself.
The copies can get passed
to a new generation
in a couple of ways.
If you're a bacterium,
you might be into cloning...
Making exact replicas
of yourself.
All your descendants
have the same DNA
and, except for an occasional
mutant, are just like you.
It's simple, it works
and genetically,
it's extremely boring.
It can also be dangerous.
If humans were all clones
everyone would have
the exact same immune system
and one successful parasite
could wipe us all out.
Fortunately, there's sex...
The method of choice for 99.9%
of the organisms on Earth
more complex than bacteria.
With sexual reproduction
two individuals
each provide some DNA.
Most animals put it
into sperm or eggs.
If the two can get together,
a new being will be created...
One that's different from
its parents and everybody else.
Where there's sex,
there's variety.
And when it comes
to survival of the fittest
variety has
a definite advantage.
All this comes at a price.
Sexual reproduction
may be popular
but it's also quite tricky.
To get an idea of how tricky
just take a peek
inside a man's testicle.
It's packed with tiny tubes,
coiled into bundles.
Stretched out,
they could cover half a mile.
Inside all this tubing,
the average man
is churning out a thousand
new sperm every second.
That's about a hundred million
new sperm every day
and more than two trillion
over a lifetime.
And here's the tricky part:
Each and every sperm
is one-of-a-kind...
Carrying a unique
genetic package.
How is this possible?
How can one person produce
so many different combinations
of genes?
The answer lies
in the very special way
we make sperm and eggs...
A process called "meiosis."
In almost every cell
of your body
you have 30,000 or more
different genes
spread out on very long strands
of DNA, called "chromosomes."
Most cells have two versions
of every gene
on a total of 46 chromosomes.
Exactly half of those, 23,
came from your mom
and 23 came from your dad.
They come in pairs, where
the partners are very similar
but not quite the same.
The only time they get together
is during meiosis.
Here's how it works inside
a testicle that's making sperm.
First, each chromosome makes
an exact copy of itself
keeping it attached
at one point.
They condense,
creating an X-shape.
Now, the chromosome partners
get together
and the two, or actually four,
will embrace.
They cling so closely
big chunks, carrying
whole bunches of genes
get exchanged
between the partners.
The cell then divides twice
each time pulling
the pairs apart.
The final result
is a sperm or an egg cell
with 23 chromosomes,
half the normal number.
By itself,
the cell is incomplete
but it still holds
incredible promise
because every chromosome now
carries a combination of genes
that has never existed before.
All this gene-shuffling means
that within a single species
there can be an enormous amount
of diversity.
And the more diversity,
the better the odds are
that someone will survive
to create a new generation.
This is my mom and dad
on their wedding day.
My mom and dad
on their wedding days.
You definitely have
your mom's eyes.
You can see I definitely have
my dad's eyebrows.
You do have your dad's eyebrows.
Melinda Tate Iruegas
and her husband, Sergio
are expecting their first baby.
Here's Mom and Dad
with me and my brother.
Oh, yeah.
My sister hadn't come along yet
but this is what
our little boy
might look like.
Their unborn child
carries a mixture of genes
not just from them,
but from all their ancestors.
Looks like the spitting image.
Mm-hmm.
You look so much like
your mother here.
But which genes got passed on
from whom
right now is anybody's guess.
Because here you are
and this is what
our little girl
might look like.
I wonder if the baby will have
the characteristic eyebrows
that comes from my father's
side of the family.
We call them
the Iruegas eyebrows.
Or that it won't
have my dad's nose.
Your nose.
It's a beautiful evening.
We talked about having children
a lot.
He's been saying,
"Five, six," you know
and I was, like, "Well,
let's start with one."
Yeah.
"You know, two,
maybe three."
and the baby likes the water.
Yeah.
In their efforts
to pass on their genes
Melinda and Sergio
pursue dramatically
different strategies.
I can't wait
for the baby to come.
Like most men
Sergio has been constantly
producing sperm since puberty.
But Melinda created all her eggs
when she looked like this...
A fetus in her mother's womb.
Within a couple of months, she
created several million eggs.
And then, the eggs began to die.
At the age of 31, Melinda may
only have a few thousand left.
But that's okay,
because inside an ovary
as opposed to a testicle
it's quality, not quantity,
that counts.
Every month,
one of a woman's two ovaries
selects an immature egg cell
to lavish with attention.
Hundreds of support cells
tend the egg
feeding it until it grows fat.
When it's ready,
the whole entourage...
The egg along with its helpers...
Oozes out of the ovary.
Waiting for them is the open end
of the Fallopian tube
which leads to the uterus.
Its tentacles capture the egg
and pull it inside.
The egg is swept along
by muscular contractions
of the tube
as well as the constant swaying
of tiny cilia.
The egg has everything it needs
to start a new life
except for one thing,
DNA from a sperm.
And it has to get it fast.
If the egg is not fertilized
within a few hours, it will die.
With sex,
there will always be pressure
to meet and impress a mate.
When it comes to actually
choosing a partner
there's a lot to consider.
For us, it might be somewhat
more complicated
than picking the one
that smells best.
But there's no doubt
that the process
can be heavily influenced
by chemistry...
Natural drugs
that flood the brain.
♪ Mi amor,
mi amor, mi amor... ♪
♪ Mi amor,
mi amor, mi amor... ♪
♪ Mi amor, mi amor,
mi amor! ♪
When love is in the air
the body can undergo
some dramatic changes.
Signals from the brain speed up
the metabolism of glucose.
As a result, body temperature
rises, skin sweats
heartbeat and breathing
get faster.
In a man, hormones cue blood
vessels to relax
allowing the spongy tissue
in the penis to fill with blood.
At the height
of sexual excitement
millions of sperm
are squeezed out of storage
and swept up by fluid
gushing from several glands
including the prostate.
The flood carries them
into a 15-inch-long tube
looping into the abdomen
and then out through the penis.
It's only about
a teaspoon of liquid
but it typically contains
about 300 million sperm.
They are immediately in peril.
The vagina is acidic,
so the sperm must escape or die.
They start to swim...
at least some of them.
Even in a healthy man
60% of the sperm
can be less than perfect
like this one with two tails.
For these guys,
the journey is over.
But what about the rest?
What are the chances
that one tiny sperm will
reach and fertilize an egg?
Sperm are often portrayed
as brave little warriors
forging their way
through hostile terrain
to conquer the egg.
Nothing could be
further from the truth.
For every challenge
the sperm face
success is, to a great extent,
controlled by the woman's body
and even the egg itself.
Take the sperm's
first obstacle, the cervix...
Passageway to the uterus.
Most of the time,
it's locked shut
plugged with mucus that keeps
bacteria and sperm out.
But for just a few days
a month around ovulation
the mucus becomes watery
and forms tiny channels
that guide the sperm through.
Arriving inside the uterus
the sperm are still about six
inches away from their goal...
At least a two-day swim.
But undulations
of the uterine muscles
propel the sperm
into the Fallopian tube
within 30 minutes.
Even a sperm that reaches
the tube in record time
has no guarantee
of fertilizing an egg.
There may be no egg there.
Ovulation could still be
days away.
It's the slowpokes... caught up
in the cilia lining the tube...
Who may have a better chance.
It's probably here that
chemicals in the woman's body
alter the sperm's outer coating.
Only those sperm
that are altered
can get a date with the egg.
The sperm are released gradually
over the course of a few days,
so at any given time
only a couple hundred sperm
will move on.
If all goes well
then farther up the tube
they'll find the egg.
But it's heavily chaperoned
by support cells
and the chaperones are picky.
Only some of the sperm
are let through.
Those who make it will face
yet another challenge.
Underneath the cloud of cells
the egg itself is encased
in a thick protein shell
called the zona.
To fertilize the egg, the sperm
must break through the zona;
but even the strongest can't
do it by brute force alone.
The egg demands
a proper introduction.
Proteins protruding
from the sperm's cap
must hook up precisely
with a set of proteins
on the egg's surface.
If they match,
the sperm is held fast
and undergoes
a dramatic transformation.
It sheds its outer coating,
releasing powerful enzymes
that dissolve a hole in the zona
allowing the sperm
to push its way through.
The final hurdle passed
the sperm still does not thrust
its way into the egg itself.
Rather, the membranes
of the two cells fuse
and the egg draws the entire
contents of the sperm inside.
I don't know.
We weren't being as careful
as we should have been
and October came around
and I was a day late
and actually I was having
some other problems,
with my wrist.
And we went to the doctor
and the doctor had asked me
was, like, "Well,
are you pregnant?"
you know, because
he wanted to do
an X ray of my wrist.
And I said, "No."
And then I thought about it
and I was, like,
"Well, I don't know."
I decided that I
better check this out.
And sure enough,
it was positive.
And when he came home,
I was like...
I could tell she had
something to tell me.
And, um...
so, I was, like
"Well, you'd
better sit down."
You just...
It was something
that we had discussed
but hadn't anticipated
until about two more years
down the road.
So when she told me,
yeah, I was ecstatic.
We were ready.
We were definitely ready
even if it was a little early.
Ready or not,
once sperm and egg get together
they have their own agenda,
to create a viable embryo.
Their chances aren't great.
It's estimated
that more than 50% of all
fertilized eggs fail to develop.
If it's going to survive, the
egg has a lot of work to do.
First, it orders the zona
to lock out all other sperm.
And then the egg
must finish meiosis
expelling half
of its chromosomes
into this tiny pouch,
called a polar body.
With the door closed behind it
the single sperm already inside
releases its precious cargo.
The sperm's 23 chromosomes
stretch out
in the roomy, welcoming egg.
The chromosomes of sperm and egg
approach each other
and then the cell divides.
Since the moment the sperm
entered the egg
24 hours have passed.
All this time
the fertilized egg is moving
down the Fallopian tube
toward the uterus.
Every few hours,
the cells divide...
Four...
eight...
sixteen...
gradually creating
the building blocks
needed to construct an embryo.
On rare occasions
the tiny cluster of cells splits
into two groups
and creates two embryos,
identical twins.
But most of the time,
the cells stick together.
They must complete just the
right number of cell divisions
before they arrive in the uterus
about five days
after fertilization.
What started
as a large, single cell
has divided into just over
a hundred much smaller cells.
But they're still trapped within
the hard shell of the zona.
Now called a blastocyst
the bundle of cells
must do two things to survive:
break out of the zona and find
a source of nourishment.
At the beginning of the sixth
day, it orchestrates an escape.
It releases an enzyme
that eats through the zona
and the ball of cells
squeezes out.
Free at last,
the blastocyst lands
on the blood-rich lining
of the mother's uterus.
It has just passed one hurdle
but is immediately presented
with another.
For, in fact, it is now
in very grave danger.
Stripped
of its protective coating
the blastocyst could be attacked
by the mother's immune system
as a foreign invader.
White blood cells
would swarm in to devour it.
In its own self-defense
the ball of cells produces
several chemicals
that suppress the mother's
immune system inside the uterus
in effect, convincing
the mother to treat it
like a welcome guest.
Then it is free to get to work.
Searching for food and oxygen
cells from the blastocyst
reach down
and burrow into
the surrounding tissue.
Eventually, they pull
the entire bundle down
into the uterine lining...
And sooner or later,
the mother will notice.
Even brushing my teeth
would make me...
the minty flavor
was just, like, gross
and make me feel nauseous.
And I would get up
and I would try to eat something
and if anything smelt...
off slightly
then it was...
it made me nauseous.
My mother has told me stories
of how my father had gone
through morning sickness.
And, of course, that never
really registered
until the first time
it started happening to me.
He literally got...
He would get really,
really nauseous
and upset
and actually get
physically ill
sometimes.
There was a couple
of times when that...
well, more than
a couple of times
when that actually happened.
Not everybody
gets morning sickness.
Sometimes months can go by
before the mother gets any sense
of the drama
unfolding within her body.
One milestone event takes place
just two weeks after conception
when the blastocyst is about
the size of a poppy seed.
This is the moment
when the cells start to organize
themselves into an embryo.
The process
is called gastrulation.
With animals like frogs
whose embryos develop
inside transparent eggs
it's easy to see it in action.
After the egg becomes
a hollow ball of many cells
some cells dive into the center,
forming layers
which will go on to develop
into different organs.
In humans, gastrulation happens
deep inside
the mother's uterine lining
so it can't be photographed.
But we think it works
something like this.
The blastocyst
creates two oblong bubbles
one on top of the other.
Sandwiched between them
is a thin layer of cells.
These are the cells
which one day may become a baby.
At the beginning of gastrulation
some cells begin moving
toward the center.
Then they dive downwards,
creating a new, lower layer.
More cells plunge through
squeezing in between,
forming a third.
The cells in the three layers
may not look different
but for each layer, a very
different future lies ahead.
The lower cells are destined
to form structures
like the lungs, liver and the
lining of the digestive tract.
The middle layer will form the
heart, muscles, bones and blood.
And the top layer
will create the nervous system
including the spinal cord
and the brain
as well as an outer covering
of skin, and eventually hair.
This is a human embryo
three weeks after fertilization.
Less than
a tenth of an inch long
its neural tube, the beginning
of the nervous system
is already in place.
A couple of days layer, the top
of the tube is bulging outwards
on its way to becoming a brain.
With the primitive
brain cells exposed
we can see
some are sending feelers
making connections
to their neighbors.
As the days pass, changes
proceed at a rapid-fire pace
throughout the embryo.
Everywhere,
cells are multiplying.
And they're on the move.
Some reach out to one another,
forming blood vessels.
A heart begins to beat.
As the embryo lengthens, the
precursor to the backbone forms.
Groups of cells
bulge out on the sides...
The beginnings of arms and legs.
This is the embryo
4½ weeks after fertilization.
It is only
about a fifth of an inch long.
The primitive backbone
now curls into a tail
which will disappear
in a few weeks.
A large brain is developing
and on the side
of the head, an eye.
How does this happen?
How does the embryo
transform itself
from a blob of cells
into different tissues
and organs
and finally into
a fully functional baby?
The secret, of course,
lies in your genes, in your DNA.
Inside most every cell
in your body
you have the same 46 chromosomes
carrying the same genes.
But not all the cells
in your body are the same.
Nerve cells...
blood cells...
cells lining your intestine...
they all look different
and they do different jobs.
That's because
in each of these cells
different groups of genes
are turned on
and when a gene is turned on
it tells the cell to construct
a particular protein.
Proteins are the molecules
that build your body...
Like collagen,
a fiber that makes up
much of your skin,
tendons and bones.
Or keratin in your hair.
Crystallin is the protein
that helps make the lens
of your eye clear.
Some proteins do work;
actin and myosin
move muscle fibers.
Hemoglobin in the blood
carries oxygen from the lungs
to the rest of the body.
So when the embryo is developing
how does a cell turn on
the right set of genes
and create the right proteins?
Part of the answer
seems to be... location.
Once the basic body plan
is established...
With a head on one end,
back and front
and left and right sides...
Cells seem to know
exactly where they are
and what they
are supposed to become.
This is because
cells talk to each other
in the form
of chemical messages.
Chemicals in one cell
can trigger a reaction
in the cell next door
that can spread
to the cell's nucleus
and turn genes on or off.
But what's really
going on in there?
How does a gene get turned on?
If all the DNA in a single cell
were stretched out
it would be about six feet long
but it's all wound up
very tightly
coiled around balls of protein.
For a gene to be turned on
something has to come in
and loosen up the right section.
Then, the cell's machinery
can latch on and read the DNA
the first step on the long road
to building a protein.
Those molecules
that can turn genes on
play a key role
in every aspect of development
including the process
that transforms the embryo
into a boy or a girl.
We didn't want to know.
We wanted to do it,
I guess, the old-fashioned way.
Well, you kind of wanted
to know.
We did a wedding-ring test
where you took
a piece of your hair
and the wedding band,
and you hold it over the belly
and if it moves one way
in a circle, then it's a girl
if it moves in a straight line
it's a boy.
And that said it was a girl.
And there was a point
when we went into the ultrasound
where I was waffling.
It was, like,
"Well, we could look.
"At this very moment
we could look
and we could find out,"
and I didn't say anything.
See, but I was
trying to be strong
because she was
very adamant about not...
I said, "No, no, no."
By the time
most ultrasounds are done
around 18 weeks or so, doctors
can sometimes make out the sex.
But in the early weeks,
it's impossible.
Take a look
at a seven-week-old embryo.
Try to guess what sex it is.
Think it's a boy?
Believe it or not, this is not
a penis... at least not yet.
It might become one
but it could just as easily
turn into a clitoris
the female sex organ.
At this stage, boys and girls
look exactly alike.
And not just on the outside.
Inside, there are two gonads
which could become testicles
or ovaries.
And there are two sets of tubes:
one in case it's a boy,
the other for a girl.
Of course, there is one way
to tell the difference...
Look at the chromosomes
in a cell from the embryo.
One pair among the 23
determines sex.
An embryo with two X chromosomes
usually becomes a girl.
If one of those Xs is a Y,
it will most likely be a boy.
Recently scientists came up with
a good idea of how this works.
There are only about 30 genes
on the Y chromosome.
One of them is called SRY.
This gene seems to function
just once in a lifetime
late in the sixth week
of embryonic development
and only in one place:
the gonad.
SRY turns on for a day or two
and the cells
churn out its protein.
But in that short time
SRY sets off
a chemical chain reaction
turning on other genes
eventually turning the gonads
into testicles
which begin
to make testosterone.
Testosterone travels
throughout the body.
If it reaches the genitals
then the cells here
will build a penis.
But if there are two
X chromosomes and no Y
different genes get turned on,
and the gonads become ovaries.
The embryo becomes a baby girl.
This is the power of genes...
Creating cascades
of chemical reactions
defining the form and function
of all the cells in your body.
Sometimes genes send the message
to multiply and grow
as with the arm and leg buds.
Sometimes the message is to die
as it is a few days later, to
the cells between the fingers.
As the weeks pass
the embryo's genes send
billions of individual messages
constructing new kinds of cells
and building organs and limbs.
Two months after fertilization
the embryo
is now called a fetus.
Almost all its organs
are in place
though they're not working yet.
The whole fetus
is just over an inch long
and weighs less
than a third of an ounce.
Over the next 6½ months
it will grow
almost 400 times larger
and prepare for birth.
All of this demands
a constant supply of nutrients.
Serge was a little frustrated
because he thought he was going
to be able to go out and get me
whatever I craved
and whatever I wanted
and I had the problem
of I didn't want anything
or crave anything
until I smelled it
and I had to smell my food
before I would eat it.
I could cook a whole meal
and if it didn't smell right
when I was done
with it, you know
just because I put
the wrong spice
in there or something
then I couldn't eat it.
Well, what about
this place here?
Let's check out the menu.
Mmm... no.
No?
No.
We would go out on walks
sometimes just
around in the square.
What do you think?
No, It's not going to work.
She would
have to smell it first.
Just see what
caught her fancy at that time.
Yeah.
Yeah?
As soon as it did
then that's where we would go.
And that lasted
throughout my entire pregnancy.
How is it?
Garlicky, yum.
Baby likes it?
Yeah, I'm pretty hungry.
I'm still like that.
I still really
want to smell my food
and if I smell something
and I'm just, like
"Oh, I have to have that,
and I have to have it now."
It's no surprise that Melinda
might be especially hungry.
The fetus she's carrying
has only one source
for all the raw materials
it needs to grow into a baby...
Melinda's blood...
Which is systematically raided
with the help of the placenta.
The placenta began to form
as soon as
the blastocyst burrowed
into the mother's uterus
and in the early weeks,
it dwarfed the embryo.
The underside of the placenta
is covered with thousands of
tiny projections, called villi
which lie in pools
of the mother's blood.
Without ever mixing
the blood of mother and child
the villi grab oxygen
and nutrients.
The enriched blood flows
about a foot and a half
through the umbilical cord,
back to the fetus
whose heart beats about twice
as fast as an adult's.
The heart is one of the few
organs that actually work
during the earliest weeks
of development.
But with other organs,
function comes later.
With the eye
although the retina and lens are
well formed by the ninth week
the fetus doesn't respond
to light
until the fifth or sixth month.
And the same for the ear.
The outer ear
quickly takes shape
but the fetus can't hear yet.
Sound conduction relies on
the tiny bones of the inner ear
and most of the bones in the
fetus start out as cartilage.
By the fourth month, hard bone
can be seen forming in the hand
and the leg.
Finally, after five months
the process is complete
in the inner ear.
And then, the fetus
begins to hear sound.
I would sing songs
right on her belly
just so that it could hear
my voice
and get to know my voice,
but there was...
And what else?
And make whale noises.
Yeah.
One of the first times
I did that
the baby seemed to move
its hand across her belly,
and kind of touch my lips
or at least I like
to think it was a hand
saying hello or something.
And I even play music.
You know, I
wanted to see
what would happen
to what different
kinds of music.
And, you know, Mozart,
it, you know, was mellow
kind of made some movements.
And then I put salsa music in
and it just started
kicking, almost
in rhythm.
So, it was great.
Got a particular beat
that it likes.
Yeah.
There's three of us dancing.
This is the baby moving.
Inside Melinda's belly
a remarkable transformation
has taken place
starting with the moment
egg and sperm met.
Inside the womb, the first weeks
are the most dramatic.
Later in pregnancy
when the mother's body seems
to be changing the most
life in the womb can appear,
well, a bit uneventful.
All the organ systems are
in place
so during the last trimester,
the fetus's main job is to grow.
But a few crucial events are
unfolding beneath the skin.
Fat deposits are forming
building reserves the baby
will rely on after birth.
But even more importantly
fat is getting laid down
in the brain.
In the sixth month, genes in
the brain order the manufacture
of a fatty substance
called myelin
which wraps around the long
connections between brain cells.
This fatty covering allows
nerve impulses to travel
up to 100 times faster,
greatly enhancing brain power.
The process will continue for
years after the baby is born.
Inhale... come up.
The brain's hunger for fat
in the last trimester
puts an enormous strain
on the mother.
Inhale.
Over the course of the pregnancy
her body has increased its own
blood supply by about 50%...
All for the sake
of the rapidly growing baby.
But late in pregnancy
the baby's need for fat
becomes so great
the mother can't keep up.
If it stays inside,
the baby will begin to starve.
Somehow, it's got to get out.
It's climbing back up now.
I've only had, like,
one anxiety attack
and it was the moment
I was in the bathroom
and I just had
the thought of, like
how's this baby
going to get out?
I just don't think
he's going to make it out.
And I hadn't really thought
about it
up until that very moment,
where I was just, like, "No."
I love you.
Giving birth is one of the most
amazing experiences
a woman can have.
It can also be
one of the most painful.
Yeah, it's starting to go down.
Remember?
Think about being
in that garden.
Again and again,
the uterus contracts
as the cervix opens up.
The tiny passageway
that once allowed
the entrance of a single file
of sperm
must now widen
to about four inches
to accommodate a baby's head.
Human births are
far more dangerous
than those of other mammals,
or even other primates.
The human brain is three
to four times bigger
than an ape's brain.
And the pelvis is narrower,
to allow us to walk upright.
A human baby has to go through
considerable contortions
to make it through
the narrow opening.
Sometimes, there is simply
not enough room.
If that happens today
Melinda's baby can be delivered
by Cesarean section.
But not long ago, before
the rise of modern surgery
death was a common outcome
for the baby and the mother.
I can't help but feel
a little guilty
that I'm responsible for this
but it's part of the natural
cycle of life
and I just want to be there
in any way that I can
to support her
through this whole process.
Because of the pain and danger
of human labor,
we regularly give birth
in the presence of others.
Today, at 4:25 a.m., Melinda's
parents, along with Sergio
will have the privilege
of witnessing firsthand
this extraordinary event...
Life's greatest miracle.
Good job, good job.
Good job.
Can you get another breath?
Terrific.
Yeah, grab it again.
Oh, that's excellent.
One more time.
Quick breath and
push it right down
some more.
Oh, good, good, good.
Good job.
Okay, stop.
Here we come!
A life! A new life!
Here we go!
4:25.
All right!
A little boy!
Hey, we have a new sound!
Look.
Look at our little boy.
Hi, sweet pea.
Hi.
Isn't he adorable?
How are you?
Look how handsome you are.
You're so handsome, mm-hmm.
We've been wondering
who you were.
Yeah... yeah,
we've been playing
with you.
Hi.
Oh, there you go.
I love that little yawn.
Wake up.
On NOVA's Web site,
follow along in real time
as an expectant mother
chronicles
the joys and challenges
of her last months of pregnancy
and the birth of her baby
NOVA is a production
of WGBH Boston.
Major funding for NOVA is
provided by the Park Foundation
dedicated to education
and quality television.
Science.
It's given us the framework
to help make wireless
communications clear.
Sprint PCS is proud
to support NOVA.
By the Northwestern
Mutual Foundation.
Some people already know
Northwestern Mutual
can help plan
for your children's education.
Are you there yet?
And by the Corporation
for Public Broadcasting
and by contributions
to your PBS station from:
to get attention.
And why?
It may be the last thing
on his mind
but this man's body
is working toward this.
Whether we're thinking
about it or not
our bodies want to make babies.
And our bodies
are very good at it.
Around the world, about 365,000
new babies get made every day.
But as ordinary as it seems
creating a new human being
is no simple feat.
Just think of it.
No matter who you are, once upon
a time, you looked like this.
From a single cell,
you built a body
that has 100 trillion cells.
You made hundreds
of different kinds of tissues
and dozens of organs
including a brain that allows
you to do remarkable things.
How did you do it?
Today, we can look closer
than ever before...
Into the womb...
into a cell...
into the essence of life itself.
Not only can we see
what's happening
but now, we're beginning
to see how it happens...
The forces that build
the embryo;
the molecules that drive
this remarkable change.
We're uncovering
the most intimate details
of how life is created...
The secrets behind
"Life's Greatest Miracle."
Captioning sponsored
by PARK FOUNDATION
NORTHWESTERN MUTUAL FOUNDATION,
SPRINT PCS
THE CORPORATION
FOR PUBLIC BROADCASTING
Major funding for NOVA is
provided by the Park Foundation
dedicated to education
and quality television.
This program is funded in part
by the Northwestern
Mutual Foundation.
Some people already know
Northwestern Mutual
can help plan
for your children's education.
Are you there yet?
Science.
It's given us the framework
to help make wireless
communications clear.
Sprint PCS is proud
to support NOVA.
And by contributions
to your PBS station from:
You might think all the people
on this beach
are just working
on their suntans.
But beneath all that sunscreen,
under the skin
there's a frenzy of activity.
Without even thinking about it
almost all the adults here
are busy
trying to reproduce.
They can't help themselves.
The urge to procreate
is a fundamental part of life
not just for us,
but for all life.
Why is this urge so universal?
At least some blame
can probably go to this...
DNA, the molecule
that carries our genes;
the chemical instructions
for building our bodies
and keeping us alive
all wrapped up
in a tiny winding staircase.
DNA has run the show for more
than four billion years
for one main reason:
It's very good
at making copies of itself.
The copies can get passed
to a new generation
in a couple of ways.
If you're a bacterium,
you might be into cloning...
Making exact replicas
of yourself.
All your descendants
have the same DNA
and, except for an occasional
mutant, are just like you.
It's simple, it works
and genetically,
it's extremely boring.
It can also be dangerous.
If humans were all clones
everyone would have
the exact same immune system
and one successful parasite
could wipe us all out.
Fortunately, there's sex...
The method of choice for 99.9%
of the organisms on Earth
more complex than bacteria.
With sexual reproduction
two individuals
each provide some DNA.
Most animals put it
into sperm or eggs.
If the two can get together,
a new being will be created...
One that's different from
its parents and everybody else.
Where there's sex,
there's variety.
And when it comes
to survival of the fittest
variety has
a definite advantage.
All this comes at a price.
Sexual reproduction
may be popular
but it's also quite tricky.
To get an idea of how tricky
just take a peek
inside a man's testicle.
It's packed with tiny tubes,
coiled into bundles.
Stretched out,
they could cover half a mile.
Inside all this tubing,
the average man
is churning out a thousand
new sperm every second.
That's about a hundred million
new sperm every day
and more than two trillion
over a lifetime.
And here's the tricky part:
Each and every sperm
is one-of-a-kind...
Carrying a unique
genetic package.
How is this possible?
How can one person produce
so many different combinations
of genes?
The answer lies
in the very special way
we make sperm and eggs...
A process called "meiosis."
In almost every cell
of your body
you have 30,000 or more
different genes
spread out on very long strands
of DNA, called "chromosomes."
Most cells have two versions
of every gene
on a total of 46 chromosomes.
Exactly half of those, 23,
came from your mom
and 23 came from your dad.
They come in pairs, where
the partners are very similar
but not quite the same.
The only time they get together
is during meiosis.
Here's how it works inside
a testicle that's making sperm.
First, each chromosome makes
an exact copy of itself
keeping it attached
at one point.
They condense,
creating an X-shape.
Now, the chromosome partners
get together
and the two, or actually four,
will embrace.
They cling so closely
big chunks, carrying
whole bunches of genes
get exchanged
between the partners.
The cell then divides twice
each time pulling
the pairs apart.
The final result
is a sperm or an egg cell
with 23 chromosomes,
half the normal number.
By itself,
the cell is incomplete
but it still holds
incredible promise
because every chromosome now
carries a combination of genes
that has never existed before.
All this gene-shuffling means
that within a single species
there can be an enormous amount
of diversity.
And the more diversity,
the better the odds are
that someone will survive
to create a new generation.
This is my mom and dad
on their wedding day.
My mom and dad
on their wedding days.
You definitely have
your mom's eyes.
You can see I definitely have
my dad's eyebrows.
You do have your dad's eyebrows.
Melinda Tate Iruegas
and her husband, Sergio
are expecting their first baby.
Here's Mom and Dad
with me and my brother.
Oh, yeah.
My sister hadn't come along yet
but this is what
our little boy
might look like.
Their unborn child
carries a mixture of genes
not just from them,
but from all their ancestors.
Looks like the spitting image.
Mm-hmm.
You look so much like
your mother here.
But which genes got passed on
from whom
right now is anybody's guess.
Because here you are
and this is what
our little girl
might look like.
I wonder if the baby will have
the characteristic eyebrows
that comes from my father's
side of the family.
We call them
the Iruegas eyebrows.
Or that it won't
have my dad's nose.
Your nose.
It's a beautiful evening.
We talked about having children
a lot.
He's been saying,
"Five, six," you know
and I was, like, "Well,
let's start with one."
Yeah.
"You know, two,
maybe three."
and the baby likes the water.
Yeah.
In their efforts
to pass on their genes
Melinda and Sergio
pursue dramatically
different strategies.
I can't wait
for the baby to come.
Like most men
Sergio has been constantly
producing sperm since puberty.
But Melinda created all her eggs
when she looked like this...
A fetus in her mother's womb.
Within a couple of months, she
created several million eggs.
And then, the eggs began to die.
At the age of 31, Melinda may
only have a few thousand left.
But that's okay,
because inside an ovary
as opposed to a testicle
it's quality, not quantity,
that counts.
Every month,
one of a woman's two ovaries
selects an immature egg cell
to lavish with attention.
Hundreds of support cells
tend the egg
feeding it until it grows fat.
When it's ready,
the whole entourage...
The egg along with its helpers...
Oozes out of the ovary.
Waiting for them is the open end
of the Fallopian tube
which leads to the uterus.
Its tentacles capture the egg
and pull it inside.
The egg is swept along
by muscular contractions
of the tube
as well as the constant swaying
of tiny cilia.
The egg has everything it needs
to start a new life
except for one thing,
DNA from a sperm.
And it has to get it fast.
If the egg is not fertilized
within a few hours, it will die.
With sex,
there will always be pressure
to meet and impress a mate.
When it comes to actually
choosing a partner
there's a lot to consider.
For us, it might be somewhat
more complicated
than picking the one
that smells best.
But there's no doubt
that the process
can be heavily influenced
by chemistry...
Natural drugs
that flood the brain.
♪ Mi amor,
mi amor, mi amor... ♪
♪ Mi amor,
mi amor, mi amor... ♪
♪ Mi amor, mi amor,
mi amor! ♪
When love is in the air
the body can undergo
some dramatic changes.
Signals from the brain speed up
the metabolism of glucose.
As a result, body temperature
rises, skin sweats
heartbeat and breathing
get faster.
In a man, hormones cue blood
vessels to relax
allowing the spongy tissue
in the penis to fill with blood.
At the height
of sexual excitement
millions of sperm
are squeezed out of storage
and swept up by fluid
gushing from several glands
including the prostate.
The flood carries them
into a 15-inch-long tube
looping into the abdomen
and then out through the penis.
It's only about
a teaspoon of liquid
but it typically contains
about 300 million sperm.
They are immediately in peril.
The vagina is acidic,
so the sperm must escape or die.
They start to swim...
at least some of them.
Even in a healthy man
60% of the sperm
can be less than perfect
like this one with two tails.
For these guys,
the journey is over.
But what about the rest?
What are the chances
that one tiny sperm will
reach and fertilize an egg?
Sperm are often portrayed
as brave little warriors
forging their way
through hostile terrain
to conquer the egg.
Nothing could be
further from the truth.
For every challenge
the sperm face
success is, to a great extent,
controlled by the woman's body
and even the egg itself.
Take the sperm's
first obstacle, the cervix...
Passageway to the uterus.
Most of the time,
it's locked shut
plugged with mucus that keeps
bacteria and sperm out.
But for just a few days
a month around ovulation
the mucus becomes watery
and forms tiny channels
that guide the sperm through.
Arriving inside the uterus
the sperm are still about six
inches away from their goal...
At least a two-day swim.
But undulations
of the uterine muscles
propel the sperm
into the Fallopian tube
within 30 minutes.
Even a sperm that reaches
the tube in record time
has no guarantee
of fertilizing an egg.
There may be no egg there.
Ovulation could still be
days away.
It's the slowpokes... caught up
in the cilia lining the tube...
Who may have a better chance.
It's probably here that
chemicals in the woman's body
alter the sperm's outer coating.
Only those sperm
that are altered
can get a date with the egg.
The sperm are released gradually
over the course of a few days,
so at any given time
only a couple hundred sperm
will move on.
If all goes well
then farther up the tube
they'll find the egg.
But it's heavily chaperoned
by support cells
and the chaperones are picky.
Only some of the sperm
are let through.
Those who make it will face
yet another challenge.
Underneath the cloud of cells
the egg itself is encased
in a thick protein shell
called the zona.
To fertilize the egg, the sperm
must break through the zona;
but even the strongest can't
do it by brute force alone.
The egg demands
a proper introduction.
Proteins protruding
from the sperm's cap
must hook up precisely
with a set of proteins
on the egg's surface.
If they match,
the sperm is held fast
and undergoes
a dramatic transformation.
It sheds its outer coating,
releasing powerful enzymes
that dissolve a hole in the zona
allowing the sperm
to push its way through.
The final hurdle passed
the sperm still does not thrust
its way into the egg itself.
Rather, the membranes
of the two cells fuse
and the egg draws the entire
contents of the sperm inside.
I don't know.
We weren't being as careful
as we should have been
and October came around
and I was a day late
and actually I was having
some other problems,
with my wrist.
And we went to the doctor
and the doctor had asked me
was, like, "Well,
are you pregnant?"
you know, because
he wanted to do
an X ray of my wrist.
And I said, "No."
And then I thought about it
and I was, like,
"Well, I don't know."
I decided that I
better check this out.
And sure enough,
it was positive.
And when he came home,
I was like...
I could tell she had
something to tell me.
And, um...
so, I was, like
"Well, you'd
better sit down."
You just...
It was something
that we had discussed
but hadn't anticipated
until about two more years
down the road.
So when she told me,
yeah, I was ecstatic.
We were ready.
We were definitely ready
even if it was a little early.
Ready or not,
once sperm and egg get together
they have their own agenda,
to create a viable embryo.
Their chances aren't great.
It's estimated
that more than 50% of all
fertilized eggs fail to develop.
If it's going to survive, the
egg has a lot of work to do.
First, it orders the zona
to lock out all other sperm.
And then the egg
must finish meiosis
expelling half
of its chromosomes
into this tiny pouch,
called a polar body.
With the door closed behind it
the single sperm already inside
releases its precious cargo.
The sperm's 23 chromosomes
stretch out
in the roomy, welcoming egg.
The chromosomes of sperm and egg
approach each other
and then the cell divides.
Since the moment the sperm
entered the egg
24 hours have passed.
All this time
the fertilized egg is moving
down the Fallopian tube
toward the uterus.
Every few hours,
the cells divide...
Four...
eight...
sixteen...
gradually creating
the building blocks
needed to construct an embryo.
On rare occasions
the tiny cluster of cells splits
into two groups
and creates two embryos,
identical twins.
But most of the time,
the cells stick together.
They must complete just the
right number of cell divisions
before they arrive in the uterus
about five days
after fertilization.
What started
as a large, single cell
has divided into just over
a hundred much smaller cells.
But they're still trapped within
the hard shell of the zona.
Now called a blastocyst
the bundle of cells
must do two things to survive:
break out of the zona and find
a source of nourishment.
At the beginning of the sixth
day, it orchestrates an escape.
It releases an enzyme
that eats through the zona
and the ball of cells
squeezes out.
Free at last,
the blastocyst lands
on the blood-rich lining
of the mother's uterus.
It has just passed one hurdle
but is immediately presented
with another.
For, in fact, it is now
in very grave danger.
Stripped
of its protective coating
the blastocyst could be attacked
by the mother's immune system
as a foreign invader.
White blood cells
would swarm in to devour it.
In its own self-defense
the ball of cells produces
several chemicals
that suppress the mother's
immune system inside the uterus
in effect, convincing
the mother to treat it
like a welcome guest.
Then it is free to get to work.
Searching for food and oxygen
cells from the blastocyst
reach down
and burrow into
the surrounding tissue.
Eventually, they pull
the entire bundle down
into the uterine lining...
And sooner or later,
the mother will notice.
Even brushing my teeth
would make me...
the minty flavor
was just, like, gross
and make me feel nauseous.
And I would get up
and I would try to eat something
and if anything smelt...
off slightly
then it was...
it made me nauseous.
My mother has told me stories
of how my father had gone
through morning sickness.
And, of course, that never
really registered
until the first time
it started happening to me.
He literally got...
He would get really,
really nauseous
and upset
and actually get
physically ill
sometimes.
There was a couple
of times when that...
well, more than
a couple of times
when that actually happened.
Not everybody
gets morning sickness.
Sometimes months can go by
before the mother gets any sense
of the drama
unfolding within her body.
One milestone event takes place
just two weeks after conception
when the blastocyst is about
the size of a poppy seed.
This is the moment
when the cells start to organize
themselves into an embryo.
The process
is called gastrulation.
With animals like frogs
whose embryos develop
inside transparent eggs
it's easy to see it in action.
After the egg becomes
a hollow ball of many cells
some cells dive into the center,
forming layers
which will go on to develop
into different organs.
In humans, gastrulation happens
deep inside
the mother's uterine lining
so it can't be photographed.
But we think it works
something like this.
The blastocyst
creates two oblong bubbles
one on top of the other.
Sandwiched between them
is a thin layer of cells.
These are the cells
which one day may become a baby.
At the beginning of gastrulation
some cells begin moving
toward the center.
Then they dive downwards,
creating a new, lower layer.
More cells plunge through
squeezing in between,
forming a third.
The cells in the three layers
may not look different
but for each layer, a very
different future lies ahead.
The lower cells are destined
to form structures
like the lungs, liver and the
lining of the digestive tract.
The middle layer will form the
heart, muscles, bones and blood.
And the top layer
will create the nervous system
including the spinal cord
and the brain
as well as an outer covering
of skin, and eventually hair.
This is a human embryo
three weeks after fertilization.
Less than
a tenth of an inch long
its neural tube, the beginning
of the nervous system
is already in place.
A couple of days layer, the top
of the tube is bulging outwards
on its way to becoming a brain.
With the primitive
brain cells exposed
we can see
some are sending feelers
making connections
to their neighbors.
As the days pass, changes
proceed at a rapid-fire pace
throughout the embryo.
Everywhere,
cells are multiplying.
And they're on the move.
Some reach out to one another,
forming blood vessels.
A heart begins to beat.
As the embryo lengthens, the
precursor to the backbone forms.
Groups of cells
bulge out on the sides...
The beginnings of arms and legs.
This is the embryo
4½ weeks after fertilization.
It is only
about a fifth of an inch long.
The primitive backbone
now curls into a tail
which will disappear
in a few weeks.
A large brain is developing
and on the side
of the head, an eye.
How does this happen?
How does the embryo
transform itself
from a blob of cells
into different tissues
and organs
and finally into
a fully functional baby?
The secret, of course,
lies in your genes, in your DNA.
Inside most every cell
in your body
you have the same 46 chromosomes
carrying the same genes.
But not all the cells
in your body are the same.
Nerve cells...
blood cells...
cells lining your intestine...
they all look different
and they do different jobs.
That's because
in each of these cells
different groups of genes
are turned on
and when a gene is turned on
it tells the cell to construct
a particular protein.
Proteins are the molecules
that build your body...
Like collagen,
a fiber that makes up
much of your skin,
tendons and bones.
Or keratin in your hair.
Crystallin is the protein
that helps make the lens
of your eye clear.
Some proteins do work;
actin and myosin
move muscle fibers.
Hemoglobin in the blood
carries oxygen from the lungs
to the rest of the body.
So when the embryo is developing
how does a cell turn on
the right set of genes
and create the right proteins?
Part of the answer
seems to be... location.
Once the basic body plan
is established...
With a head on one end,
back and front
and left and right sides...
Cells seem to know
exactly where they are
and what they
are supposed to become.
This is because
cells talk to each other
in the form
of chemical messages.
Chemicals in one cell
can trigger a reaction
in the cell next door
that can spread
to the cell's nucleus
and turn genes on or off.
But what's really
going on in there?
How does a gene get turned on?
If all the DNA in a single cell
were stretched out
it would be about six feet long
but it's all wound up
very tightly
coiled around balls of protein.
For a gene to be turned on
something has to come in
and loosen up the right section.
Then, the cell's machinery
can latch on and read the DNA
the first step on the long road
to building a protein.
Those molecules
that can turn genes on
play a key role
in every aspect of development
including the process
that transforms the embryo
into a boy or a girl.
We didn't want to know.
We wanted to do it,
I guess, the old-fashioned way.
Well, you kind of wanted
to know.
We did a wedding-ring test
where you took
a piece of your hair
and the wedding band,
and you hold it over the belly
and if it moves one way
in a circle, then it's a girl
if it moves in a straight line
it's a boy.
And that said it was a girl.
And there was a point
when we went into the ultrasound
where I was waffling.
It was, like,
"Well, we could look.
"At this very moment
we could look
and we could find out,"
and I didn't say anything.
See, but I was
trying to be strong
because she was
very adamant about not...
I said, "No, no, no."
By the time
most ultrasounds are done
around 18 weeks or so, doctors
can sometimes make out the sex.
But in the early weeks,
it's impossible.
Take a look
at a seven-week-old embryo.
Try to guess what sex it is.
Think it's a boy?
Believe it or not, this is not
a penis... at least not yet.
It might become one
but it could just as easily
turn into a clitoris
the female sex organ.
At this stage, boys and girls
look exactly alike.
And not just on the outside.
Inside, there are two gonads
which could become testicles
or ovaries.
And there are two sets of tubes:
one in case it's a boy,
the other for a girl.
Of course, there is one way
to tell the difference...
Look at the chromosomes
in a cell from the embryo.
One pair among the 23
determines sex.
An embryo with two X chromosomes
usually becomes a girl.
If one of those Xs is a Y,
it will most likely be a boy.
Recently scientists came up with
a good idea of how this works.
There are only about 30 genes
on the Y chromosome.
One of them is called SRY.
This gene seems to function
just once in a lifetime
late in the sixth week
of embryonic development
and only in one place:
the gonad.
SRY turns on for a day or two
and the cells
churn out its protein.
But in that short time
SRY sets off
a chemical chain reaction
turning on other genes
eventually turning the gonads
into testicles
which begin
to make testosterone.
Testosterone travels
throughout the body.
If it reaches the genitals
then the cells here
will build a penis.
But if there are two
X chromosomes and no Y
different genes get turned on,
and the gonads become ovaries.
The embryo becomes a baby girl.
This is the power of genes...
Creating cascades
of chemical reactions
defining the form and function
of all the cells in your body.
Sometimes genes send the message
to multiply and grow
as with the arm and leg buds.
Sometimes the message is to die
as it is a few days later, to
the cells between the fingers.
As the weeks pass
the embryo's genes send
billions of individual messages
constructing new kinds of cells
and building organs and limbs.
Two months after fertilization
the embryo
is now called a fetus.
Almost all its organs
are in place
though they're not working yet.
The whole fetus
is just over an inch long
and weighs less
than a third of an ounce.
Over the next 6½ months
it will grow
almost 400 times larger
and prepare for birth.
All of this demands
a constant supply of nutrients.
Serge was a little frustrated
because he thought he was going
to be able to go out and get me
whatever I craved
and whatever I wanted
and I had the problem
of I didn't want anything
or crave anything
until I smelled it
and I had to smell my food
before I would eat it.
I could cook a whole meal
and if it didn't smell right
when I was done
with it, you know
just because I put
the wrong spice
in there or something
then I couldn't eat it.
Well, what about
this place here?
Let's check out the menu.
Mmm... no.
No?
No.
We would go out on walks
sometimes just
around in the square.
What do you think?
No, It's not going to work.
She would
have to smell it first.
Just see what
caught her fancy at that time.
Yeah.
Yeah?
As soon as it did
then that's where we would go.
And that lasted
throughout my entire pregnancy.
How is it?
Garlicky, yum.
Baby likes it?
Yeah, I'm pretty hungry.
I'm still like that.
I still really
want to smell my food
and if I smell something
and I'm just, like
"Oh, I have to have that,
and I have to have it now."
It's no surprise that Melinda
might be especially hungry.
The fetus she's carrying
has only one source
for all the raw materials
it needs to grow into a baby...
Melinda's blood...
Which is systematically raided
with the help of the placenta.
The placenta began to form
as soon as
the blastocyst burrowed
into the mother's uterus
and in the early weeks,
it dwarfed the embryo.
The underside of the placenta
is covered with thousands of
tiny projections, called villi
which lie in pools
of the mother's blood.
Without ever mixing
the blood of mother and child
the villi grab oxygen
and nutrients.
The enriched blood flows
about a foot and a half
through the umbilical cord,
back to the fetus
whose heart beats about twice
as fast as an adult's.
The heart is one of the few
organs that actually work
during the earliest weeks
of development.
But with other organs,
function comes later.
With the eye
although the retina and lens are
well formed by the ninth week
the fetus doesn't respond
to light
until the fifth or sixth month.
And the same for the ear.
The outer ear
quickly takes shape
but the fetus can't hear yet.
Sound conduction relies on
the tiny bones of the inner ear
and most of the bones in the
fetus start out as cartilage.
By the fourth month, hard bone
can be seen forming in the hand
and the leg.
Finally, after five months
the process is complete
in the inner ear.
And then, the fetus
begins to hear sound.
I would sing songs
right on her belly
just so that it could hear
my voice
and get to know my voice,
but there was...
And what else?
And make whale noises.
Yeah.
One of the first times
I did that
the baby seemed to move
its hand across her belly,
and kind of touch my lips
or at least I like
to think it was a hand
saying hello or something.
And I even play music.
You know, I
wanted to see
what would happen
to what different
kinds of music.
And, you know, Mozart,
it, you know, was mellow
kind of made some movements.
And then I put salsa music in
and it just started
kicking, almost
in rhythm.
So, it was great.
Got a particular beat
that it likes.
Yeah.
There's three of us dancing.
This is the baby moving.
Inside Melinda's belly
a remarkable transformation
has taken place
starting with the moment
egg and sperm met.
Inside the womb, the first weeks
are the most dramatic.
Later in pregnancy
when the mother's body seems
to be changing the most
life in the womb can appear,
well, a bit uneventful.
All the organ systems are
in place
so during the last trimester,
the fetus's main job is to grow.
But a few crucial events are
unfolding beneath the skin.
Fat deposits are forming
building reserves the baby
will rely on after birth.
But even more importantly
fat is getting laid down
in the brain.
In the sixth month, genes in
the brain order the manufacture
of a fatty substance
called myelin
which wraps around the long
connections between brain cells.
This fatty covering allows
nerve impulses to travel
up to 100 times faster,
greatly enhancing brain power.
The process will continue for
years after the baby is born.
Inhale... come up.
The brain's hunger for fat
in the last trimester
puts an enormous strain
on the mother.
Inhale.
Over the course of the pregnancy
her body has increased its own
blood supply by about 50%...
All for the sake
of the rapidly growing baby.
But late in pregnancy
the baby's need for fat
becomes so great
the mother can't keep up.
If it stays inside,
the baby will begin to starve.
Somehow, it's got to get out.
It's climbing back up now.
I've only had, like,
one anxiety attack
and it was the moment
I was in the bathroom
and I just had
the thought of, like
how's this baby
going to get out?
I just don't think
he's going to make it out.
And I hadn't really thought
about it
up until that very moment,
where I was just, like, "No."
I love you.
Giving birth is one of the most
amazing experiences
a woman can have.
It can also be
one of the most painful.
Yeah, it's starting to go down.
Remember?
Think about being
in that garden.
Again and again,
the uterus contracts
as the cervix opens up.
The tiny passageway
that once allowed
the entrance of a single file
of sperm
must now widen
to about four inches
to accommodate a baby's head.
Human births are
far more dangerous
than those of other mammals,
or even other primates.
The human brain is three
to four times bigger
than an ape's brain.
And the pelvis is narrower,
to allow us to walk upright.
A human baby has to go through
considerable contortions
to make it through
the narrow opening.
Sometimes, there is simply
not enough room.
If that happens today
Melinda's baby can be delivered
by Cesarean section.
But not long ago, before
the rise of modern surgery
death was a common outcome
for the baby and the mother.
I can't help but feel
a little guilty
that I'm responsible for this
but it's part of the natural
cycle of life
and I just want to be there
in any way that I can
to support her
through this whole process.
Because of the pain and danger
of human labor,
we regularly give birth
in the presence of others.
Today, at 4:25 a.m., Melinda's
parents, along with Sergio
will have the privilege
of witnessing firsthand
this extraordinary event...
Life's greatest miracle.
Good job, good job.
Good job.
Can you get another breath?
Terrific.
Yeah, grab it again.
Oh, that's excellent.
One more time.
Quick breath and
push it right down
some more.
Oh, good, good, good.
Good job.
Okay, stop.
Here we come!
A life! A new life!
Here we go!
4:25.
All right!
A little boy!
Hey, we have a new sound!
Look.
Look at our little boy.
Hi, sweet pea.
Hi.
Isn't he adorable?
How are you?
Look how handsome you are.
You're so handsome, mm-hmm.
We've been wondering
who you were.
Yeah... yeah,
we've been playing
with you.
Hi.
Oh, there you go.
I love that little yawn.
Wake up.
On NOVA's Web site,
follow along in real time
as an expectant mother
chronicles
the joys and challenges
of her last months of pregnancy
and the birth of her baby
NOVA is a production
of WGBH Boston.
Major funding for NOVA is
provided by the Park Foundation
dedicated to education
and quality television.
Science.
It's given us the framework
to help make wireless
communications clear.
Sprint PCS is proud
to support NOVA.
By the Northwestern
Mutual Foundation.
Some people already know
Northwestern Mutual
can help plan
for your children's education.
Are you there yet?
And by the Corporation
for Public Broadcasting
and by contributions
to your PBS station from: