The Human Body

You're looking at a baby's heart.

It's beating 120 times a minute.

But, amazingly, it's not the only thing keeping this human being alive.

That's done by the most sophisticated life-support machine on Earth.

To find that machine, we have to leave the heart

and travel through an artery the thickness of a drinking straw.

Every one of us has an almost identical network of arteries and veins.

Identical, that is, except for this one.

No one watching has a blood vessel like this.

It's a spiralling link between this body and its life-support.

And at its end, a mass of tubes so tiny even blood cells appear huge.

Through a wall comes the sound of the engine room.

It's a mother's heart, and we've just made the journey

from inside the heart of her unborn baby.

This film is the story of the unique relationship between mother and baby

which is at the start of every new life.

0ver a hundred million acts of sexual intercourse take place each day in the world.

These result in around 910,000 conceptions

and, nine months later, 400,000 babies.

Many of those babies will be first glimpsed like this, with ultrasound.

But we can see them differently.

Stack a hundred ultrasound pictures together and a new image emerges:

a remarkable three-dimensional picture of a child yet to be born.

Today, new technology is letting us see the world of the unborn in a completely new way.

It also lets us retrace its past from a baby just before birth

to a foetus of thirteen weeks.

And further back, unravelling the dazzling complexity of the embryo at six weeks...

and four...

and three...

..until we're back at the beginning, with the cells that start the whole thing off.

An egg,

and a hundred times smaller, a single sperm.

The process looks so elegant you'd think it was simple.

But you'd be wrong.

These are my sperm, amazingly about 500 million of them

from a single ejaculation.

With just this one ejaculation it should be possible

to impregnate all the fertile women of Western Europe.

And I'm nothing special.

In actual fact, we need all these millions of sperm

to have any realistic chance of achieving just one pregnancy.

Why? Because pregnancy is difficult.

It's a struggle to get pregnant,

it's a struggle to stay pregnant,

it's a struggle to give birth and it's a struggle to be born.

By filming every two weeks, we squeezed the nine months it takes to create a new life

into less than a minute.

Having a baby is a common enough experience and we feel we know a lot about it.

But more than half of what's actually going on inside our bodies is a mystery even to doctors.

It's our greatest achievement and yet it's cloaked in secrecy.

And even when we live through it, experiencing the months of pregnancy first hand,

our bodies still conceal the marvel that's going on within.

In this film I want to look at that time afresh,

over a single day...

and over 300 days.

We'll follow the complexities and difficulties of the beginning of life.

We'll condense a year into just a few minutes

and reveal how, moment by moment, month by month, a struggle to be born unfolds.

And we'll show how, time after time,

the human body has to overcome the most daunting of obstacles

to complete the everyday miracle of new life.

I think we talked fairly quickly about having children.

I think we decided fairly quickly not to have them straight away.

Yeah, but it was never an issue as to whether we would or wouldn't, I think.

We just both assumed we would.

It was something that didn't have to be discussed as a possibility or a definite no-no.

It was more a question of when.

Phillippa and Jeff Watson live in Bath. They're both in their thirties.

Five months ago, they started trying for a baby.

I assumed very much that as soon as Phillippa came off the Pill

that getting pregnant would be a piece of cake, but I'm not sure that's the case.

Well, I definitely thought, because all my previous experience

has been about contraception and how important it is,

I thought it would be very easy to get pregnant.

There would be no problem at all, but, in fact, that's not the case.

The more you read, the more you talk to other people,

you discover that it's actually not that easy.

And, er, my opinion at the moment is that I wonder how people actually do get pregnant.

Seems very, very difficult.

And Phillippa is right, it is difficult.

There are only about 30 days a year when a woman has a chance of becoming pregnant.

And even on one of those days a whole chain of unrelated events needs to click into place.

Success depends on a cycle that's been part of a woman's life since puberty.

With a new medical imaging technique developed especially for this series,

we can see inside Phillippa.

Nestling deep in her pelvis lies Phillippa's uterus - her womb.

It's a mass of muscle in which a baby could one day grow.

From the top of the uterus on either side comes a Fallopian tube,

reaching out towards one of her ovaries, here coloured white.

This is where her lifetime store of eggs is waiting.

They were all formed when Phillippa was just an eight-week-old embryo.

At puberty something remarkable happened.

Inside Phillippa's brain a tiny gland, her pituitary,

signalled to her ovaries to start to release some of those eggs.

Since then, month after month, that's what's happened.

And though it's never been shown on television before,

you're about to see what ovulation looks like.

We're inside one of the Fallopian tubes, heading towards the ovary.

And at the end of the tube, there it is.

That huge white moon is her ovary.

Inside it is an egg about to be released.

Suddenly, the surface of the ovary breaks, revealing a red wound.

It looks enormous, but it's actually only a couple of millimetres across.

The end of the Fallopian tube rubs against it in time with the woman's pulse.

Then, at the bottom of the wound, a tiny hole appears.

And hidden within is the egg.

A strand of sticky, almost see-through cells is pulled away by the rubbing Fallopian tubes.

They're nurse cells, up to five million of them, ready to feed and nurture the egg.

The egg itself is deep within them.

This is ovulation.

It will happen just 400 times in a woman's life.

It is the beginning of the possibility of new life.

As the egg is pulled from the ovary into the Fallopian tube,

the race to pregnancy has begun.

Inside the folds of the Fallopian tube, the egg and its sticky entourage are squeezed along.

But time is already running out.

The egg has perhaps just 24 hours to be fertilized.

After that it'll die.

And to be fertilized it needs to meet a vital ingredient:

sperm.

I'm sometimes asked what's the best way to make sure

a sperm meets an egg in those vital 24 hours.

The answer's rather technical: have sex and have it often.

As our bodies come nearer and nearer to orgasm, every part gears up in anticipation.

Sperm have to travel through the tangle of tubing in the testicle

to the end of the erect penis.

It's a distance of nearly a metre.

The white fluid they're in is mainly nutrients for their long journey ahead.

At orgasm, huge muscular contractions propel the fluid

on its final ride through the man's body and into the woman's.

And now, inside the vagina, sperm face the first of many mortal dangers.

The walls of a woman's vagina are coated in acid

to protect her from infection by bacteria.

But it's lethal to sperm.

Within minutes, the walls are littered with the corpses of millions.

And within an hour most of the 500 million sperm that set off are dead.

Yet the woman's body can help, as well as hinder the sperm's progress.

It's possible the contractions of her orgasm help to draw sperm into her uterus.

0r even that the junction between the vagina and the uterus, her cervix,

is dipped time and time again into a pool of waiting sperm.

It's also likely that in the hours after sex the uterus itself contracts,

helping to carry the sperm on their way.

Even so, the sperm have been all but annihilated.

0nly a few thousand will complete the journey across her uterus

and into her Fallopian tubes.

Then, minutes, hours or even days after they started out,

the sperm that have struggled so far will find what they set out for.

Deep in the folds of the Fallopian tube, here magnified a thousand times - an egg.

As they get near, the sperm are lured towards their goal

by a chemical signal sent out from the egg.

Each sperm carries in its head all the genetic information the man will contribute,

and this now needs to meet with the mother's genetic information waiting inside the egg.

Suddenly one of the sperm, which has been burrowing into the wall of the egg,

breaks right through.

Inside the egg, the genetic information is gathered in two tiny balls.

Details from Phillippa are in one and from Jeff in the other.

In a moment the information will fuse together.

And the instant that happens the unique inherited characteristics of a new life

will be fixed.

All the information from Phillippa and Jeff is now there

to determine whether their baby will be a boy or a girl,

tall or short, have blue eyes or brown.

Even whether it's predisposed to heart disease or certain kinds of cancer.

But, as yet, the baby itself does not exist.

In fact, the chances of the fertilized egg surviving are far from certain.

Some will do nothing.

But just over half will do this.

It makes a copy of itself and divides, again and again.

Seen down the lens of a laser microscope, the dividing egg looks like a strange berry.

It's a cluster of eight identical cells.

But they won't be identical for long.

As Phillippa and Jeff continue life as usual,

they're completely unaware of the changes going on inside Phillippa's body.

Hour after hour, the fertilized egg continues to change,

and all the time it's journeying along her Fallopian tube towards her uterus.

Her uterus, too, is transforming.

Its lining has swollen and thickened.

We're seeing a part of the lining magnified almost ten thousand times.

It's the landing ground for the fertilized egg.

But the egg establishes itself in the womb in a very unexpected manner

that will set the tone for the next nine months.

This is Hirudo medicinalis,

better known to you and me as a leech.

It's a parasite.

It takes whatever it needs to live

by sucking the blood of whatever it can latch on to.

In this case, that's me.

As it sucks my blood, it takes from it all that it needs to live.

It literally lives off me.

And the whole of pregnancy is shaped by a similar kind of parasitic relationship.

Unlike the leech, the developing embryo doesn't suck the mother's blood.

But it does raid her blood for the raw materials it needs to grow.

From the word go, both leech and embryo are out for themselves.

The cells of the embryo spread out as they divide and invade the mother's uterus.

It's almost an aggressive attack.

But, surprisingly, the army of foreign cells

does not meet any resistance from the mother's own defence systems.

If anything else grew inside her at the same tireless rate,

it would either be killed or eventually it would kill her.

Quite how the embryo pulls off this life-saving trick remains a mystery.