Original subtitles

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[narrator] From

the moment of conception...

The clock is running.

Cells multiply.

Chemicals react.

Bone, tissue, and blood

are manufactured.

It's the final leg

of the incredible

nine-month journey

that made us.

When our eyes open

for the first time

as our sense of vision

switches on,

when our lungs prepare

for the first breath

as, in a moment,

we have to face

the outside world...

[baby crying]

...and survive on our own.

It all must come together

with exquisite precision

because one mistimed event

or faulty gene

could have

a life-changing effect.

-[horn blows]

-[crowd cheering]

[narrator]

To survive on the outside,

there's one vital part

of the body

that must be ready

for anything.

It gives your body

its shape and strength.

The skeleton.

[whistle blows]

An adult skeleton is made up

of over 200 bones...

[whistle blows]

Which gives us shape

and movement.

They protect

your vital organs.

[crowd cheering]

And muscles

attached to the ribs

enable your lungs to expand

and fill with air.

[athlete] Set! Hut!

[narrator]

And it's in the womb

that this phenomenal

architecture is built.

Without it, our bodies

have no structure at all,

making it virtually

impossible to survive.

But there's one little girl

who has defied all the odds.

Janelly is nine-years-old,

but she looks

over half her age

because when she was born,

her body lacked

the ability to make bones.

[woman speaking Spanish]

[translator] We love Janelly

with all our hearts,

and we try to give her

lots of love

because we thought

maybe tomorrow

we won't have her anymore.

[speaking in Spanish]

[narrator]

Janelly has an extremely

rare bone disorder

called hypophosphatasia.

It went undetected in

the womb,

but shortly after

she was born,

her parents started

to realize

something was wrong.

[woman speaking Spanish]

[translator]

I started noticing it

about three or four weeks

after her birth.

She wasn't growing.

She wasn't putting

on weight.

It got really, really bad.

[narrator]

Janelly's condition affects

every bone in her body,

including her skull.

When she was born,

she had to rely on

a ventilator to breathe

because she had

no ribs to protect

her lungs,

and doctors didn't know

if her brain was damaged.

We all began without bones

in our body.

As the body first

takes shape,

it begins

by growing cartilage,

the soft, flexible tissue

that forms the foundation

of what, in time,

becomes our skeleton.

Then over several months,

a magical process unfolds.

Bit by bit, this cartilage

starts to harden into bone.

By week 25, the pelvis,

our largest bone,

is forming.

Our bones are formed

by special cells

called osteoblasts.

They swarm around

the skeleton

coating the soft cartilage

with a hard,

calcium-based mineral.

[crowd cheering]

But this process

also produces

a damaging chemical

which stops our bones

from hardening.

So the body has developed

a response.

A gene is activated,

creating a crucial protein,

TNSLAP, that neutralizes

the damaging chemical,

letting bone formation

continue.

But Janelly lacked

this all-important gene

that enabled cartilage

to continue the process

of turning into strong bone.

[woman speaking Spanish]

[translator] She was on

the verge of death

many times.

[man speaking Spanish]

[translator] They told us

the best thing to do

would be to disconnect her

there and then

because she wouldn't be able

to have any quality of life

and she couldn't

go on suffering.

[Dr. Simmons]

All right, Janelly.

[narrator] Dr. Jill Simmons

has been treating Janelly

for the past seven years.

Gonna listen to you.

Yes. We are.

[woman speaking Spanish]

She couldn't move

her arms and legs.

She couldn't lift

up her head.

She couldn't even really

turn her head right to left.

[Janelly laughing]

Her lungs had nothing

to hold them open

with no ribs.

It was a really

sad situation,

um, because the truth is,

without your bones,

you, you can't breathe.

You can't eat.

You can't even move.

It, it's really...

It's, it's really not

compatible with life.

[narrator] But then

out of the blue came hope.

News of a new drug

being trialed in Australia.

[Dr. Simmons]

We had heard about the drug,

but it was very early

in the clinical trial.

There was almost

nothing known

about it at this point,

but at, at this point

in Janelly's life,

there was also

no other option.

So this was when

she was at her worst.

[narrator] Compared

to an X-ray of a normal

18-month-old child's,

Janelly's made grim viewing.

It showed

a total lack of bones.

[Janelly cooing]

Bone development takes place

not just in the womb,

but also all the way through

to our teenage years.

Janelly's doctors

didn't know whether

the drug would help her,

but they hoped that it might

allow her to form bones.

[Janelly cooing]

We offered it

to her parents,

and they took a

leap of faith

and decided to try it.

[narrator]

After an agonizing,

six-month wait,

they X-rayed her,

and what they saw

was amazing.

The drug appeared to replace

the missing protein

Janelly's body

couldn't produce.

Janelly had started

to develop real bones.

[Dr. Simmons]

I think when you

look at the X-rays,

it's one of the most

miraculous things

that I've ever seen

as a doctor.

Here we were,

seeing bones grow

from where there had been

no bones before,

and it was

an incredible experience.

High five!

Mommy.

[laughs]

[speaks Spanish]

[speaking Spanish]

[woman speaking Spanish]

[translator] The doctor

came in and told us,

"We've got wonderful

news for you."

We looked at each other,

and he said,

"Janelly is starting

to have bones."

We said, "Thank God."

[narrator] Doctors

don't know how far

Janelly's

miraculous recovery will go

or if she will walk one day.

[Dr. Simmons]

You know, to see a child

who probably

would not be alive

anymore now happy

and growing bone

and breathing on her own,

I mean,

that's why we all get into

medicine in the first place.

To really of been a part

of something that

had no hope

and really turn it

to something

that is so positive

has been incredible.

[narrator]

But everyone is hoping

she will grow stronger

all the time,

continuing to defy the odds.

[man speaking Spanish]

[translator] Our plan

for her is to go on

looking after her,

take it day by day

as she improves,

and not lose hope

that someday

she will be able to walk

and lead a normal life.

[narrator] Now 26 weeks,

and the fetus is about

one-foot long,

weighing around 24 ounces,

and every day,

it's growing in size.

Deep inside the veins,

vital changes

are taking place.

The fetus has been producing

its own blood,

which carries oxygen

to every tissue in the body,

delivering the energy

that fuels

its extraordinary growth.

But it can only do this

thanks to a special kind

of blood.

Fetal blood cells contain

a different kind

of hemoglobin

than adult cells,

with a greater affinity

for oxygen.

It allows the baby to absorb

oxygen from the

mother's blood

through the placenta.

But now in the 26th week,

the fetal blood

is slowly changing

into adult blood,

which will be able

to take its oxygen

from the air outside

the womb.

[monitor beeping]

Not all blood

ends up the same.

There are 35 different

blood groups,

and within these groups,

a blood type

is based on antigens

which can form

thousands of different

combinations.

Our blood type is defined

by the genes we inherit

as well as random mutations

that may occur in the womb.

And the one we end up with

may affect the way

we live our lives.

[crying]

[Thomas]

When I heard about my blood,

I thought, "Oh,

I really have

to be careful."

You never know

what can happen.

[narrator]

Thomas has Rhesus

null blood.

It's the rarest type

in the world.

Only 41 people

have ever been found

with the same blood as him.

Thomas is a librarian.

He walks to work

because he has

to avoid all risks.

If anything happened to him,

finding a blood donor

would be almost impossible.

[Thomas]

Consciously or not,

I've tried to find

a safe activity,

safe, uh, work.

[narrator] Thomas' blood

has to be stored in Paris

and Amsterdam.

A long way to go

should he be in any danger.

Early in pregnancy,

proteins and sugars

known as antigens

appear on the surface

of each blood cell.

And it's the presence

or absence of these antigens

that determines blood type.

Most of the time,

we aren't aware of antigens,

but our immune system

will attack blood

from someone

with incompatible antigens.

It could cause

the blood to congeal,

which can be

life-threatening.

Some antigens

are high-prevalence,

which means they're found

in the red blood cells

of most people,

so most of us have blood

that's compatible

with other blood types.

But some blood types

are incredibly rare

because random

genetic mutations

can knock out blood groups,

and when this happens,

it makes finding a donor

much harder.

In Thomas' case,

an incredible coincidence

of two genetic mutations

left his blood cells

devoid of a whole group

of antigens.

It means that his blood

is the closest thing

to universal blood

that anyone else

could receive,

but should Thomas

need a transfusion,

he would be in trouble,

as his blood attacks

almost all other types.

I know that I have to be

really careful in my life.

But, uh, there is one thing

I, I cannot resist.

[wind whistling]

I feel this kind of freedom.

I can forget everything,

and I feel well.

It might be risky,

but, uh, as long as I can,

yes, I will do it.

[narrator] Thomas

never leaves home

without his documents

showing the location

of the nearest source

of his rare blood.

Everywhere I go, I have

my blood information

with me.

This is the paper

which says which type

of blood I have

and that in case

of emergency, uh,

they can call, uh, Paris,

and they are also in contact

with Geneva.

[narrator] With only

two places in Europe

that have compatible blood,

it's essential

he avoids accidents.

I touch wood

it never happens.

[chuckles]

[narrator]

With bones hardening

and blood maturing,

the incredible march towards

being a living,

breathing baby

is well under way.

It's time to prepare

for the world

and the people we'll meet

once we're born.

[Kerstin muffled]

"Old mother Hubbard

went to the cupboard

to fetch her poor dog

a bone."

[narrator] And to do that,

we'll need our senses,

first of which to develop

is our hearing.

[Kerstin muffled]

"Once she got there,

the cupboard was bare,

and so

the poor doggy had none."

[narrator] No bigger

than a grain of rice,

this amazing, coiled,

snail-like structure,

the cochlea, is the sensory

organ for our hearing.

"She went to the baker's

to buy him some bread.

[muffled]

But when she came back,

the poor dog was dead."

[narrator]

Sound waves cause fluid

inside of the cochlea

to move,

a motion that is picked up

by 30,000 tiny hair cells.

[low rumbling]

At 28 weeks, sounds coming

from the outside world

should spark these tiny

hair cells into life,

sending signals to our brain

which we interpret as sound.

[static signals]

And it's time for Kerstin

to find out

if her baby has developed

the sense of hearing.

[man] So we can see

the internal structure of

the baby's brain.

And there's the baby's

little cheeky face

looking at us.

[Kerstin] Oh, it's amazing

how much it's grown.

[machine whirring]

[narrator]

We want to discover

if Kerstin's baby can hear,

so we've devised

a simple test.

To make sure that mom

can't subconsciously

influence

her baby's responses,

we are going to shut out

the outside world.

[squeaking]

Yeah. It's definitely

changing the pattern now.

-Baby put his hand over

his face when it started.

-[man 2] Did it?

[narrator] Changes

in the baby's heart rate

when we make sounds...

-[whistle blows]

-[doctor] And again.

-[ringing]

-[rattling]

[narrator] ...suggests

we can hear in the womb.

But do we remember

any of those sounds we hear?

-Are we capable

of forming early memories?

-[squeaking]

At the top of your body,

the most important organ

of them all

is beginning to

get organized.

Cells are developing,

connecting every

region together.

Most of the brain's growth

is now in the wiring.

Our new connections

are growing fatty sheaths

that insulate them

and create the circuits

that will form the mind.

"Old mother Hubbard

went to the cupboard

to fetch

her poor doggy a bone.

But when she got there,

the cupboard was bare,

and so the poor doggy

had none.

[muffled]

She took a clean dish

to get him some tripe.

When she came back,

he was smoking a pipe.

She went to the fishmonger's

to buy him some fish..."

[narrator] In a study,

a group of pregnant women

read a rhyme to their unborn

babies every day

for six weeks.

"When she came back,

he was dancing a jig.

She went to the cobbler's

to buy him some shoes,

and when she came back,

he was reading the news.

She went

to the seamstress..."

[narrator] They then stopped

for a couple of weeks

before starting to read

to them again...

"She went to the hatter's

to buy him a hat.

She went to the joiner's

to buy him a coffin...

When she came back,

the poor dog was laughing.

She went to the barber's

to buy him a wig."

[narrator]

And what they found was

because they were now

familiar with the rhyme,

their heart rates dropped.

[muffled voice]

They became nice and calm,

but when they were read

an unfamiliar rhyme,

there was

no response at all.

[Kerstin muffled]

"She went to the baker's

to buy him some bread,

and when she came back,

the poor dog was dead.

She went to the joiner's

to buy him a coffin.

But when she came back,

the poor dog

was laughing..."

[narrator] Suggesting

that lingering in the back

of their mind

was a memory of the stories

their mothers had read them.

[heart beating]

Even before birth,

the brain can store

memories,

but these memories

will not last.

No one is capable

of recalling

memories from the womb

because the brain areas

that store memories

long-term

won't be developed

until after

two and a half years of age.

This is also a time that

our other senses evolve.

[heart beating]

At 29 weeks in the enclosed

world of the womb,

something amazing

is happening.

We're starting to see.

[muffled plane radio]

Nestled deep

in the South Pacific

-is this tiny atoll.

-[plane engine whirring]

For your eyes,

it's a feast of beauty,

yet this place is known

as "Color-Blind Island."

At the back of our eye

on the retina,

light-sensitive cells

called rods and cones grow.

At 29 weeks,

our rods are so sensitive

that this allows us to see

a black-and-white image.

But from now on,

a momentous change begins.

The cone cells

are being wired up,

which will allow us

to see color.

Light-sensitive proteins

will convert red,

green, and blue,

the separate components

of light entering our eyes

into nerve impulses.

These are sent to

the brain and interpreted

as a color image.

[electrical charges]

But if these vital proteins

misfunction,

the world will look

like this

24-7 for your entire life.

With their cones

not working,

the affected islanders

all struggle

with the painful, burnt-out

image when the sun is up.

[man speaking

local language]

[translator]

I find it difficult

to go outside in the sun.

When it's sunny,

I cannot see to do my work.

[children laughing]

[narrator] It's not

just the sensitivity

of their eyes

that's the problem.

Being color-blind

affects all aspects of life.

[woman speaking

local language]

[translator] When it comes

to cooking food,

my daughter has a hard time.

We need to inspect the food

before she cooks it,

because she can't tell

if it's off.

[man speaking

local language]

[translator]

That's a beautiful dress.

What color is it?

[laughing]

[man speaking

local language]

[translator] None of these

bananas are ripe.

[speaking local language]

[translator] We cannot see

what colors are there.

We see the colors,

but they say it's wrong.

What do you see here?

Do you see any numbers?

Nothing.

[narrator] Most people

aren't really color-blind,

but color-deficient.

Being able to distinguish

20 of the 100 hues

most people can see.

But, intriguingly, 10%

of the population

of Pingelap

are destined to live

in a totally

black-and-white world.

[children playing]

In 1780, Pingelap was all

but wiped out by a tsunami.

A community of just

20 people survived,

one of which was their king.

He was believed

to have been color-blind.

Scientists believe

he had a fault in a gene

that allows us to see color,

and he passed this down

to his children.

[thunder rumbles]

[bell ringing]

[bell ringing]

[singing hymn]

Because of the remoteness

of the island and

its religion

that discourages

marriage to outsiders,

this genetic fault

has been passed down

through the generations.

[singing continues]

And continues to affect

the population today.

[indistinct chattering]

But as the sun goes down,

they gain

an amazing advantage.

[man speaking

local language]

[translator] I can see

the land mass

and small lagoon.

I can see also the big rock.

[narrator] You and I

have no chance of seeing

what Herrol can see,

but our super

sensitive camera

reveals, amazingly,

he really can see

in the dark.

So it could just be that

the part of Herrol's brain

that normally interprets

color is now being used

as extra processing for his

monochrome night vision.

In the middle of the night,

Herrol and his friends

are hunting flying fish.

They are attracted

to the flame

and fly towards it

as if it's moonlight.

[Herrol speaking

local language]

[translator]

This type of fishing is fun,

especially if we

catch plenty.

My family is expecting

fresh fish.

We can't just go to market

and buy food.

Even though it's hard,

it's what we do.

It's our job.

[narrator] During our time

in the womb,

we go through the most

incredible transformation

from a single cell to a baby

that's able to make sense

of its world.

A lot of what makes you

who you are,

from your height

to the color of your skin,

is decided by the genes

you inherit from

your parents,

but these are nothing

like as inflexible

as we once thought.

We're discovering

that the outside world

influences genes

in the womb,

preparing the fetus

for what is to come.

This is the new science

of epigenetics,

and it may help explain

the rise of one

of the developed world's

most serious diseases...

Diabetes.

I used to eat fish and

chips and Indian food.

Snacks over here,

coffee time.

[narrator] Freddie and Lal

have very similar lives.

-Subway...

-Potato chips...

Dunkin' Donuts...

Sweets, something salty.

[narrator] They live

in the same city.

They do the same job.

They even eat

the same type of food.

[Lal] Twenty-four hours,

everywhere is open.

Subways are running.

Even sometimes

you're not hungry,

you eat the burger.

You eat the burger.

After a while, you go

to have a cup of coffee.

You want to have some donut

or some candy.

You never give a rest

to your stomach. [laughs]

You keep eating

and keep eating.

[narrator] But Lal,

unlike Freddie,

has developed

type-2 diabetes.

His body is no longer

able to regulate

the sugar in his blood.

[Lal] When I find out

I'm diabetic

and my doctor tell me,

I was a bit, a bit shocked.

I was, really, I thought

I'm going to die soon.

He... You know,

my doctor said,

"Nothing is going

to happen like this,

but you have to take care

of yourself.

You have to take

the medicine

the rest of your life

and watch what

you're eating."

[narrator]

But some scientists

believe that the secret

as to why Lal has diabetes

and Freddie doesn't

can be traced back

to the womb.

They were both born

in India...

[cycle bell rings]

...but with

one crucial difference.

[Freddie] I was born

and brought up in Mumbai,

and, uh,

it's a very fast life,

uh, 20 million people.

[Lal]

I'm born Punjab.

My village was

a small village,

and life was very simple.

[narrator]

Like millions of Indians,

Lal's life is very different

to his mother and father's.

They lived a rural life.

[Lal]

Life was totally different

here and there,

and over there,

we was eating

all the natural food.

Rice, some dal, some rotis,

some vegetables,

and over and over,

and we was very happy.

[narrator] The theory

is that if mom's diet

was low in fat, sugar,

and calories,

then her baby adapts.

It becomes

incredibly efficient,

built to extract

as much energy as it can

from the low-calorie foods

available.

[cars honking]

The problem comes

when you end up

living in a very different

environment.

Lal's diet is very different

to his parents,

much richer in fat, sugar,

and calories,

and, unfortunately,

it's not the kind of diet

that his body was programed

in the womb to expect.

As a result, statistically,

Lal is more likely

to be obese

or develop diabetes.

He fits large

population studies

that have tracked people

who were born in villages

and moved to cities.

They are far more likely

to develop diabetes

later in life.

[bell rings]

In contrast, Freddie's mom

would have been eating

a much higher

calorific diet.

Fries with that...

Number five, fries.

[narrator] Living

in the busy city of Mumbai.

[Freddie]

Recently, I've been eating

Italian food,

pizzas and all,

Spanish food.

The other day,

I had Brazilian food.

[narrator] It seems

Freddie was built in

the womb for city life,

and this doesn't only apply

to Freddie and Lal,

but to populations

throughout the world.

They are part of

a global trend

as people move

from the country

to the city.

We're living through the

greatest migration

in history

and with it,

an increase in diabetes.

While we have identified

a trend,

the actual process

of how a mother's diet

affects her baby is unclear,

but there are clues,

and these can be found

in an extraordinary

epigenetic study

carried out

on some very special mice.

These mice have been bred

so that they're

genetically identical,

but they look

completely different.

Unbelievably,

the only difference is,

the mom of the little

brown mouse

was given food supplements

during pregnancy,

things like folic acid

and vitamin B12.

Crucial genes were switched

on and off,

a process called

methylation,

leading to a normal,

healthy, brown mouse,

but the mother of the mouse

with the ginger coat

was not fed

these supplements,

and the genes

remained unaltered.

He is not only

bigger and fatter,

but also much more

vulnerable to things like

cancer and diabetes.

In mice, at least,

if the mother's diet

is deficient

in essential nutrients,

it can have

life-changing effects

on her offspring.

And we're beginning

to suspect

that this may well be

the case in humans, too.

[Lal] I think the diabetes

is like the gift

I have from America.

You see, all my sisters

and my brothers,

they're living in India.

They're not...

None of them

have diabetes.

But still, I love America.

[laughs]

[narrator] Although

we can't say for sure

that Lal's disease

is a result of nutrition

in the womb,

the statistics in

the mice study

strongly points us

in that direction.

And all around the world,

the hunt is on

for other epigenetic forces

that could permanently

change our DNA.

[train horn blows]

Seventeen years ago,

Quebec was in the middle

of the worst ice storm

in living memory.

[cars honking]

The community

was thrown into turmoil.

[siren blaring]

[Julie]

Outside was very,

very scary.

We didn't know

what's happening,

and we don't have any radio,

so we don't have any news.

We have no phone,

no electricity,

so, uh, we were alone,

very, very, very alone.

We didn't see the light

on the end of the tunnel.

Uh, it was like a war zone,

[chuckles]

I mean, war zone.

[narrator] The ice storm

left a trail of destruction,

but the landscape wasn't

the only thing affected.

Vincent's life may have been

changed forever

because his mom Julie

was in her last months

of pregnancy at the time.

Julie was one of hundreds

of expectant mothers

trapped by the storm

living under extreme stress

who later became part

of a unique human study.

It's long been wondered

what impact stress can have

on children in the womb,

and the ice storm

gave Dr. Suzanne King

a unique chance to find out.

[Dr. King] There are

very few studies in humans

on prenatal stress.

It just would not be ethical

to submit a pregnant woman

to stress to see what,

what effects it has

on the children.

But with a natural disaster,

mother nature randomly

distributes the stress.

[Julie]

I was wondering,

"Are we going

to have enough wood?

Are we going to have

enough, uh, food?"

We had no money.

Banks were closed,

so what are we gonna do?

And we were 22 days

without electricity.

[narrator]

Julie was 35 weeks pregnant,

and living without

any power at all.

She was under severe stress

at a vital time in

the development of her baby.

The question for

Professor King

was whether this stress

had been passed on

to the unborn children

during the storm.

That's the day

Vincent was born.

He was eight pounds,

40--14 ounces.

Here, he's about

two weeks,

about two weeks.

[narrator] Professor King

had to play

an extraordinarily

patient game.

She closely monitored

the children as they grew,

testing their mental

and physical development,

as well as analyzing

their DNA

at various stages.

Here is Vincent

with a Santa Claus.

[narrator] From three

to 15 years of age.

That's at four-years-old,

and now at 17.

[laughs]

[Vincent speaking French]

[translator]

I've had two MRI's.

I've done saliva tests.

I've done memory tests.

[heart beating]

I'm happy to do this

because it's for science

to help the world develop

and find out

if it's had an effect

on my life.

[heart beating]

[narrator]

When Professor King

analyzed her data,

the results were shocking.

[heartbeat quickens]

[horn blares]

Children

in the high-stress group

had significantly impaired

language and motor skills.

[exclaiming]

At the age of two, they were

using 30% fewer words

than those

in the low-stress group,

and the health

of the high-stress group

was also worse.

They were more likely

to suffer from autism,

asthma, and obesity.

[Julie] Vincent,

he has a lot of allergy

to dairy food, nuts,

and, uh, seafood,

and Vincent has

problems with language.

He's seen a therapist about

that for about seven years.

[crowd cheering]

Why is he allergic? Why?

Nobody in the family

had food allergy.

Nobody have problems

to speak.

[narrator] But what's

even more remarkable

is that Professor King

discovered that the stress

the children

had been exposed to

had left a unique signature

in their DNA.

While we're developing

in the womb,

a complex process known

as methylation takes place.

It can switch some genes on

and others off,

which alters the way

our genes actually work.

And this process

can be affected

by the environment

we're exposed to.

[crowd cheering]

And this is what

Professor King discovered.

She found a direct

correlation

between the amount

of methylation

in the DNA of the children

in the high-stress group.

[crowd cheering]

And the number of days

that their mothers

had lived without power

during the ice storm.

[King]

So, for example, the greater

the number of days

without electricity,

the lower the IQ

of the child,

the lower their, uh,

language development.

Um, even, uh, the way

they played was different.

These affects

could be massive.

[narrator] There's still

a long way to go

before we can

completely understand

how the outside world

influences the way

we are built,

but Professor King's study

proved for the first time

that the environment

we're exposed to in the womb

can have an effect

on our genes,

and these changes

can continue to affect us

for the rest of our lives.

It's now around 36 weeks

and nearing the end

of our development.

All of the vital organs

are built and tested...

...except one.

For our entire time

in the womb,

our lungs lay dormant,

flooded with liquid,

but strangely,

we practice breathing

in anticipation of that

first air-filled breath.

[muffled inhalation]

[muffled exhalation]

[Sam] The whole aim of

the game is to be as relaxed

as possible,

so no stress, no worry,

getting into your own little

world, disappearing, really.

[muffled exhalation]

You kind of focus inward,

and you get very in tune

with what your heart rate

is doing

and what your levels

of oxygen are

and whether you need

to breathe or not.

Your mind is under

more control,

and you're not panicking,

you're not worrying.

You're just keeping

everything

slow and relaxed.

[narrator]

Sam regularly pushes

her lungs to their limit.

She is a free diver.

She can explore

the depths of this lake

on one single breath

for minutes at a time

without coming up for air.

[Sam] It's very quiet,

it's very peaceful.

It can be very beautiful.

You haven't got your phone

to think about.

You haven't got any beeps

or distractions

or people calling for you.

There's none of that

going on,

so it is quite

a private space, really.

You're in a real moment

of peace and serenity,

and, and you kind of

tune into

that nothingness

and enjoy that

instead of everyday life.

[muffled inhalation]

[narrator] Our lungs

have been growing

like branches of a tree,

and now,

just weeks from birth,

a massive flood

of growth hormone

kicks off a vigorous change.

Thousands of tiny saccules

blossom.

These are alveoli,

the secret to breathing.

It's incredible that Sam

practices the sport

of free diving.

Her lungs never got

the chance to fully develop.

[Sam] I was born six weeks

premature back in 1972,

and at that stage, six weeks

premature was quite severe.

I mean, it's still

not that great today,

but it was quite a big deal

in those days.

It was quiet scary

for my parents, apparently.

It also meant that

I was born

without everything,

perhaps, grown to how strong

it should before...

Before I was born,

especially my lungs.

[narrator] Being premature

means Sam developed

far fewer alveoli.

Her lungs have

a reduced capacity

for absorbing oxygen.

But, amazingly,

Sam has overcome

the disadvantage

she was born with

and has trained herself

to be able to dive

for up to five minutes.

[Sam] If you don't

really know how far

you can go

or how long you can stay,

and sometimes you might

overstay your welcome.

If you get too excited

or nervous,

then your heart starts

racing.

Your diaphragm

starts to contract,

and then you need

to come up,

so you've got to be

very in control of

your thought processes

and, to some extent,

of your body.

If you know that you've

got some weaknesses

and you, uh,

take care of that

with your life

with how you eat,

how you exercise,

what you do,

it doesn't

need to be obsessive.

If you are looking

after yourself,

means you can do the things

that you love doing.

It's possible.

You just got to work at it

maybe a little bit harder

than somebody, perhaps,

who wasn't born premature.

[narrator]

Sam is living proof that,

whatever the circumstances

of your first breath,

how you live your life

and the choices you make

can help you to overcome

those early obstacles.

After nine months

of development,

the body is fully built.

One single cell

has transformed

into trillions

of different cells.

In an astonishing concert

of biology,

25,000 genes have activated

at just the right time.

Floods of hormones

have signaled

the most miraculous

and life-changing

transformation.

But now the tiny human

has outgrown its resources,

and it's time to leave

the comfort of the womb.

Around 280 days

after this miraculous

journey first started...

The countdown

to birth begins.

The hormone oxytocin

triggers contractions

which increase in intensity.

[people speaking

indistinctly]

[woman 1 groaning]

[woman 2]

Well done. Well done.

[narrator]

The cervix gradually

starts to dilate

over many hours...

[breathing deeply]

Until the baby moves

into the birth canal.

The baby is preparing

for a monumental change

to take place.

The lungs must switch

from an unused

sack of liquid

to an organ filled

with air.

[man] Big push for me,

big push.

[people speaking

indistinctly]

[woman 2] Another big push.

You still got

contractions...

-[woman 2] Another big push.

-[people speaking

indistinctly]

[woman 2]

Here take a breath in.

Another big push.

[people speaking

indistinctly]

[people speaking

indistinctly]

[groans]

[ticking increases]

There we go.

[man] Oh, wow!

That was quick.

-Oh, little baby.

-[woman 2] Well done!

[narrator] And with

the first breath,

the nine-month journey

is complete.

-Oh, that's just it!

Thank you very much.

-[chuckles]

3.972, which is

eight pounds, 12.

[man] It's a boy...

Eight pounds, 12 ounces.

[narrator] Birth, of course,

is just the beginning.

From now on,

we will learn, grow, adapt.

Our life will be

immeasurably enriched

by our relationships

with other people,

but our time in the womb

will have left

an indelible mark.

It will have shaped

our futures in so many ways.

After all, these were

the nine months

that made you.