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In the Womb -

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(generated from captions) of a nine-month-long journey. This baby has come to the end

smell, touch and learn. She can already taste, hear, Sounds are louder. She is feeling jostled and squeezed. and uncomfortable. Her living space has become cramped from the calm and comforting cocoon She is about to be forced the only world she's known, that has been and terrifying new world. and thrust into a noisy, bright

(Woman groans) MIDWIFE: Wonderful. Hang on. (Groans) Good girl. of the incredible journey This is the story inside her mother's womb, this little girl has taken to a full-grown baby from a single cell

in just nine months. And again. Come on.

the journey of her life, She may be about to begin the most dramatic nine months. but she's already completed In just 38 weeks,

from a single cell this baby has transformed of over 200 different types, into trillions of cells self-sustaining life - organised into a complex, a human baby girl. scanning techniques New 3-D and even 4-D

open a window into the womb, unfold before our eyes. allowing us to see foetal development

based on scientific observation Real footage and computer imagery as never seen before. take us on a journey inside the womb The foetus behaves in a manner than ever previously imagined. that is much more complex

the foetus will smile, During her odyssey in the womb, recognise her mother's voice and maybe even dream. The mother may provide the nest, food, water and oxygen, she may provide the vital elements - is the foetus itself, but the real star of the show along an intricate set of plans building, dividing and growing

created at the moment of conception. During ejaculation, up to 500 million sperm a mature, healthy man expels inside a woman's vagina,

and the incredible journey begins. the father's genetic code. Each sperm carries a precious cargo - are constantly at work, A man's testes every second. churning out over 1,000 sperm is affected by the man's lifestyle. The quality of these sperm healthier sperm He will make stronger,

excessive alcohol, if he avoids smoking, hot baths and tight underwear. Coffee, on the other hand, to swim further, faster and harder. has been shown to stimulate sperm the smallest cell in the human body. It's a slow journey for the sperm -

three millimetres a minute They travel at just and there are hurdles at every turn. they pass through the cervix, From the vagina, and on into the fallopian tube, up into the uterus the largest cell in the body - where the woman's egg -

is waiting. a woman's ovaries release one egg Each month, containing her own genetic code. she was still a foetus herself, She made these eggs while nestled inside her own mother's womb. ever since, They've been kept in storage and into adulthood, through childhood and adolescence

ready to burst into life. find their way to the egg How the sperm is something of a mystery. that sperm have a sense of smell Recent research indicates and could sniff their way to the egg. for the sperm The journey is so long and arduous

that only a handful will survive. the actual moment of conception. It may take up to 10 hours before are the strongest and fittest. The first sperm to reach the egg through the egg's surface The first one to burrow its head will be the winner.

for coming second. There are no prizes The instant one sperm enters the egg,

in the egg's membrane it triggers a change for any other sperm to get through. which makes it impossible

Once inside the egg, now detached from its tail, the head of the sperm, of the egg. is drawn towards the nucleus the two nuclei fuse. At this moment, The egg is now fertilised. will become a new human life. This is the first cell of what

in these bundles called chromosomes - The genetic code is stored and 23 from the father. 23 from the mother a super-coiled strand of DNA - Each chromosome is made of a double helix the molecule shaped like

that carries our genetic code. contains over two metres of DNA. Each microscopic chromosome A pattern of chemical codes and hold the key to our uniqueness - create this twisting ribbon of DNA our genes. to make a human - It takes between 20 and 25,000 genes

roughly the same number as a chicken. from each of our parents Each of us has a complete set of every cell in the body. deep in the nucleus Our genes are a set of instructions rather than a fish or a tree, that tell us to become a human, exactly what kind of person we'll be. as well as deciding

is responsible for a specific trait - Each gene, or combination of genes,

the colour of our skin, how many legs we'll grow, instead of wings, that we'll have arms no tail, a big nose. others completely hidden. Some genes will be dominant, and genetically unique. Each one of us is physically

an equal contribution Our parents make to most of our genetic makeup. is all down to the father. But the sex of the child

The 23rd pair of chromosomes of determining sex. has the specific job that comes from the mother The sex chromosome is always the same - type X.

from the father But the one that comes X for a girl could be one of two types - for a boy. or Y, a much smaller chromosome, for many months, Although they won't know it that won the race, for these parents it was an X sperm and they're going to have a girl. The genes she has inherited her looks, much of her character - will have already predetermined

a thrill seeker or good at music, whether she's stubborn, intelligent, to certain diseases, and even her vulnerability or diabetes. like cancer, schizophrenia

will depend on many things - The exact course of her life

her whole environment. her friends, her family, much of her future is foretold. But at the instant of fertilisation,

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The fertilised egg is on a journey, travelling along the fallopian tube towards the safety of the uterus. About a day after fertilisation, the egg divides for the first time. Every cell in the body will need its own copy of the genetic blueprint. The chromosomes reproduce first,

making an identical copy of the entire genetic code. When the two sets of chromosomes have parted, the nucleus splits into two and the cell divides.

This process of division continues as the clump of cells travels down the fallopian tube. After four or five days, the tiny ball, now called a blastocyst, has grown to around a hundred cells, and it begins to separate into two sets.

The outer ring of cells is destined to become the placenta, while the inner clump will become the embryo itself. At this stage, these inner cells are known as stem cells. Stem cells have the remarkable capacity to turn into any one of over 200 different types of cell.

They can grow into any part of the body. After seven days, the blastocyst reaches the end of the fallopian tube and arrives in the uterus - a haven for the next nine months.

More than a week has passed now since conception,

but until she misses a menstrual cycle, the mother may not even realise she's pregnant. Pregnancy is divided into three blocks, or trimesters. In the first trimester - the first three months - the single egg transforms itself into a blueprint for the fully formed baby.

All the features of the human body - limbs, nerves, organs, muscles - will be mapped out in the fragile first nine weeks. The embryo is now starting to take shape.

During the third week, the embryonic ball of cells, no bigger than a pinhead, folds in on itself to form a long tube. The top of the tube is growing into the head, and the trunk of the body stretches down below.

The head doesn't look much like a head yet, but at day 15, nerve cells begin to form in what will become the brain as well as in the spinal column, exposed and totally unprotected by skin or bone.

Inside her body, the mother is creating a safe world for the baby to grow, protected from the outside, nestled in a cocoon.

As soon as she becomes pregnant, drastic changes sweep through the mother's system. Her blood volume may leap by up to 50% to cope with the extra demand for oxygen from the parasitic growth in her womb. Once the embryo embeds itself in the uterus,

it will start to draw from the mother's bloodstream all it needs to grow.

Another of the first organs to form is the heart. Until now, the heart has been a dormant clump of muscle cells.

But after 22 days, it bursts suddenly into life, when still just the size of a poppy seed. One cell spontaneously contracts, triggers its neighbours and sets off a chain reaction,

until all the heart cells are beating. The muscle cells in the heart are pre-programmed to contract. Later on, when the nervous system is more developed, the brain will carefully control the rate of contraction, keeping it steadily beating and pumping for the rest of the child's life. If she lives to 75, that will be nearly 3 billion heartbeats. Without a heart, there is no way of spreading around the food and oxygen the embryo needs to flourish. Now, with the heart pumping, primitive blood cells start to circulate in the foetus through veins no thicker than a hair, bringing vital supplies of oxygen and food to fuel the frantic growth.

HEARTBEATS In just three weeks, the embryo has formed the beginnings of a nervous system and a heart

that is capable of pumping nutrients round its tiny body. Some women pick up on the incredible events unfolding inside them, and, alerted by hormonal changes, may realise they're pregnant without the aid of a test. This thin blue line on a home pregnancy test is triggered by hormones in the mother's urine. It may be the first clue of the changes that are about to happen over the next eight months.

After four weeks, the embryo is no bigger than a kidney bean,

and is growing by about 1mm every day. Black dots on the head are the beginnings of eyes. The miniature single-chambered heart beats 80 times a minute

and is getting faster every day. There are buds along the body that will grow into arms and legs.

Plates of tissue growing in from four sides put the face together. The top section grows down to make the forehead and nose. The cheeks fold in from the side, joining up to form the top lip. Even in adulthood, we bear a clear mark from this join - the vertical groove between the mouth and nose, called the filtrum.

If the sides don't join up properly, then the baby will develop a cleft palate and may need surgery to correct this once she's born. At day 30, even an expert would find it difficult to tell, just from looking at it, if this embryo is going to become a human, a pig, or an ape.

Just 1.5% of our genes make us human. We share 98.5% of our DNA with chimpanzees, three-quarters with dogs, half with fruit flies, and a third with daffodils. For the next few weeks, the embryo will continue to grow

according to its own internal genetic blueprint, and will become more like a potential human. The foetus has been growing now for six weeks. It is about 2cm long and the whole thing would fit neatly inside a walnut.

Just black dots a few days ago,

the eyes are now glassy, sightless domes with no eyelids set widely apart. The head itself is still massive compared to the body. Even at birth, the head will be a quarter of the baby's body length.

The rest of the body won't catch up with the head until adolescence. After growing for eight weeks,

the embryo looks more like a tiny human, and becomes known as a foetus,

which in Latin means 'offspring'.

She has reached an important milestone. Until now, the embryo was dependent on the nutrients she could extract via her yolk sac, a floating balloon connected to the base of the umbilical cord. A human yolk sac is not like a chicken's. It contains no yolk to store food.

For the first few weeks, it is believed to generate nutrients and blood cells for the tiny embryo. By two months, the yolk sac has become redundant and shrivels away. The crucial job of feeding and nurturing the foetus has been completely taken over by the placenta, a liver-like slab at the end of the umbilical cord

embedded into the wall of the uterus. The placenta is the foetus's life support system during her time in the womb. It's a network of very fine blood vessels reaching into the wall of the uterus. Like the roots of a tree sucking nutrients from the soil, it extracts everything the foetus needs

from the mother's bloodstream - food, oxygen, water - and passes it into the foetus's blood. FOOD SIZZLES Blood enriched by the mother's diet then travels through the umbilical cord into the foetal arteries. Everything the foetus doesn't need - all the waste products - are siphoned out by the placenta and passed back to the mother's bloodstream. CHILD: Mum! KNIFE CHOPS The placenta also filters out many harmful substances that may be in the mother's bloodstream

but which could damage the foetus. But it can't stop everything, and the mother has to be careful with things like prescription drugs, alcohol, nicotine, which will pass directly to the foetus. Some pregnant mothers have an instinctive reaction to avoid food or drink that could be harmful to the baby. They may be revolted by the smell of alcohol or seafood, meat or mushrooms.

The mother's body is effectively controlling her intake of food, telling her what to avoid and instigating cravings to ensure her child gets what it needs - nothing more, nothing less. The first trimester can be an uncomfortable time for the mother. Apart from its nurturing role, the placenta also controls pregnancy by producing hormones. This hormonal surge in the early months is what gives some women morning sickness. One of these - progesterone - is secreted throughout the term and prevents the mother releasing any more eggs.

Others stop the mother's immune system rejecting this unfamiliar growth inside her. ELECTRICITY CRACKLES Another week passes, and the nervous system is now developing fast, spreading connections throughout the body. The nervous system generates an average of 2.5 million neurones every minute of the baby's nine-month stay in the womb. The foetus has been still so far. But now, at about nine weeks, her whole body begins to twitch. Movement will play a crucial role in stimulating the growth of muscles and strengthening of joints. At this stage, the nerves may only extend from the muscles of the leg, for example, back to the spinal cord. The connection to the brain is still growing. So the brain is not yet controlling the foetus's movements. They are still involuntary reflex spasms. Nor is the heart yet controlled by the brain, but it beats automatically and spasmodically. It has been picking up speed since it burst into life in the third week. After starting at a feeble 20 to 25 beats per minute,

it now pumps as fast as it will ever go -

a frantic 157 beats every minute. An adult heartbeat is normally 70 to 80. After this peak, the heart rate will ease off as the heart, along with the rest of the body, gradually comes under the brain's control.

The foetus is 10 weeks old and until now, has been hidden from the world. But the mother is about to get her first glimpse of the secret events unfolding inside her womb.

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Between 10 and 14 weeks, a pregnant woman will usually go for her first scan. Ultrasound scans have revolutionised our understanding of foetal development as well as our provision of care for pregnant women.

MAN: So here we have your little baby here. Oops! Now, there's a bit of activity going on now. Professor Stuart Campbell of the Create Health Clinic in London is one of the world's leading experts in obstetrics. Can you see the head? The baby's looking to the side.

And it will all make sense to you when the baby starts to move. WOMAN: OK. The pictures are produced by sending ultra high frequency sound waves - far too high for us to hear - from the probe into the body of the mother. The waves penetrate through internal tissue, passing easily through fluid areas like amniotic fluid but bouncing back strongly off solids like bone.

You can see one, two, three...

The reflected waves are collected to produce an internal image, similar to an X-ray but without the danger. Ultrasound scans are not known to cause any harm to the foetus. That's the face up there. Good.

Ultrasound waves don't travel well through air so the scans are less effective looking through an adult's stomach or intestine, for example, which are riddled with air pockets. But inside the womb, the foetus lives in fluid. Even the lungs are filled with fluid, and the ultrasound produces a moving image which, to a trained operator, will reveal much about the health and development of the foetus.

We have to make sure. This is the cerebellum.

This first scan is also a chance to establish a more accurate due date based on the baby's size, rather than guessing from the date of the last menstrual period. So it's 82.9mm... ..for the grand long length, OK? Now, just do the nuchal translucency because you haven't had that test. OK. The scan can also show early - but not conclusive -

diagnostic features pointing towards genetic abnormalities. No, that's a test for Down syndrome. It doesn't definitely say the baby's got Down syndrome or not, but it tells you if you're at risk. Until recently, non-invasive research into the development of the human foetus has been restricted to analysis of stillborn specimens

or what can be gleaned from grainy, two-dimensional ultrasound scans. But now this area of exploration has been revolutionised with the development of three-dimensional scans, and even more remarkably, 3D scans which move in real time, known as 4D scans.

WOMAN: Oh, look! Clamped with hands on face. For obstetricians, this tool has been the equivalent of the Hubble Space Telescope, and for the first time, it has been possible to open up a window on the womb and to see babies growing before our eyes. These images show the incredible range of behaviour

that even a very young foetus is capable of. Obstetricians can directly observe how the foetus grows, how it behaves, how it reacts to stimulation, how its reflexes help it prepare for birth and for survival outside the womb. Professor Campbell is a world-renowned pioneer of these new scans and is responsible for taking these incredible images. This scan shows a 30-week foetus yawning. And this one, a 32-week foetus playing with its nose. These 4D images are some of the earliest ever taken of a foetus in the womb. This shows an embryo of just six weeks. The foetus is on the left and the yolk sac - still bigger than the foetus - is on the right. Here an embryo of just eight weeks, less than 3cm long, is making its first movements.

As well as checking the health of the baby, this scan will be the first opportunity to tell if you're pregnant with one baby or two or more. Multiple births run in families. If your mother's family has a history of non-identical twins, then you are far more likely to have twins yourself.

Identical twins are formed when an egg splits in two. The twins will be in the same sac in the womb and will share a placenta. If two eggs are released and fertilised at the same time, then the twins will be non-identical or fraternal. In this case, the twins will be separated in the womb, each twin living in its own amniotic sac.

They will also have separate placentas and the blood flow to each twin is carefully monitored throughout pregnancy. Other than a slightly early birth, there may be no further complication. Even though she won't be able to walk until she's around a year old, the building blocks to her first steps are there after just 11 weeks in the womb. These 4D scans show 11- and 12-week-old foetuses kicking and pushing out their legs in what is known as the stepping reflex.

A reflex action is a pre-programmed biological impulse. When her feet touch the base of the uterus, the nervous system triggers an automatic muscle reaction in the legs. At this age, there is so much space in the uterus, the foetus bounces and leaps around,

using the walls of the womb as a trampoline. The ability to walk is an important survival skill. And the more the foetus moves, the stronger the reflex will grow.

You can clearly see this stepping reflex in newborns when you dangle their feet on the ground. The period from 6 to 11 weeks has seen the most dramatic transformation of the entire pregnancy,

with the foetus undergoing a metamorphosis and growing nearly five times bigger in a frantic five-week burst. Over 200 different types of cell have been made. Muscles and nerves are twitching. There is a liver, two kidneys, a stomach no bigger than a grain of rice. All the elements of a human baby have been formed and it's still only seven centimetres long.

BABY'S HEART BEAT THUMPS At this point, after 12 weeks, the foetus enters the second trimester - the middle three months of pregnancy. Although tiny still - no bigger than a fist - she's now less delicate and there is less risk of a miscarriage.

Miscarriages are most common in the first three months, when new cells are developing. An imbalance in the immune system, stress, if the mother has previously given birth to a boy, could all increase the risk. Only 50% of fertilised eggs survive all the way through pregnancy. In most miscarriages, the mother is unaware of what has happened

and may mistake her miscarriage for a heavy period.

As they develop, initially male and female foetuses have identical genitals. Both sexes have a protuberance, which for boys will become a penis,

and for girls, a clitoris. At 12 weeks, the only difference is that they stick out at different angles. Looking at an ultrasound, an expert might guess the sex of the baby based on this angle, but it will be a few more weeks before there is a clear difference between male and female genitals. But in each case, the sex organs will already be hard at work. For a male, the testicles will be producing testosterone and the ovaries of a baby girl will already be busy making her own supply of eggs.

After 4 months, the foetus will be up to 14 centimetres long. The nervous system is up and running and her movements are increasingly coming under the control of her brain. She is much more mobile now. Muscles are flexing, fingers and toes are separate and defined and bones are hardening. Hands develop before the feet. This could be because hands are going to be used first once the baby is born. Or it could be because the hands, being important sensory organs, develop at the same time as all the other senses are beginning to form.

The eyes are now closer together,

giving the foetus a more human look. ZAPPING The central nervous system has now extended connections from the brain to most parts of the body. And the brain is establishing total control. The heart, for instance, is no longer beating spontaneously and spasmodically. Instead, the brain regulates the muscles and keeps them pumping blood at a steady 140 to 150 beats per minute - roughly twice an adult's heart rate. Using a Doppler probe, it is now possible to hear what the baby's heart sounds like. BABY'S HEART BEATS

MAN: That's 146 beats per minute - the heart. See? Which is just the right beat. As the nervous system extends throughout the foetus, so too does her capacity to respond to stimulus. She is becoming sensitive to touch, and if prodded through the mother's abdomen, she may squirm. From 16 weeks gestation, the foetus makes lots of intricate movement. She can bend, flex and twist fingers, hands, wrists, knees and toes and is already beginning to develop an awareness of the space around her. It's called proprioception. This unconscious sense of body and space helps us to interact with our environment.

We take in information from a variety of sensory organs - eyes, ears, nose and limbs - and we build up a mental understanding of the outside world. As we grow up, we take for granted the ability to coordinate our movements - to stand without falling over, to run and jump and roll down a hill.

We have an understanding of where our body is and what it's doing

that has been developed and refined over the course of our early lives from a constant system of feedback. This control is something we've been developing since we were in the womb. This 4-D scan shows actual footage of a foetus reaching up to touch her head.

In these computer-generated images, the movements have been taken directly from observations of the 4-D scans. Sensors give constant feedback to the brain and the movement can then be refined and gradually perfected.

As the foetus explores her body, she will spend a lot of time practising her grasping reflex, grabbing hold of her hands, feet, fingers, toes and even her umbilical cord, sometimes getting it tangled around her body.

It is, however, very long.

By the end of pregnancy, it will be over half a metre and very elastic.

It presents no danger at this stage. The grasping reflex is something of a puzzle, as it offers a newborn baby no life-saving advantage to be able to cling tightly to things.

The answer may lie in our ancestry. Life is relatively simple for a newborn human. She will be carried around with her mother in either arms or sling or pram. For a newborn ape, survival depends on the ability to cling to the fur of her mother as she forages for food or escapes from predatory claws. With their mothers' lack of fur and a stable family life,

human babies today are less dependent on this reflex for survival. The foetus will, however, still develop an incredibly strong grip.

After about 18 weeks,

the foetus's digestive system is beginning to work. She has no need to eat or drink... ..but as you can see in this real 4-D image, she begins to swallow the fluid she floats in - the amniotic fluid. Some indigestible waste will gather in her intestine in the form of a greeny-black paste called meconium. But most of the fluid will pass through her urinary system back out to rejoin the amniotic fluid. Round about this time, when the foetus is about 18 weeks old, the mother may become aware of her growing baby's movements for the first time.

Although the foetus has been active for quite some time, it's only now that the movements are strong enough for her to feel. Women who have previously been pregnant will be more alert to this slight fluttering sensation and may pick it up when the baby is just 15 weeks old. The eyes, now in their correct position, are generally thought to remain fused shut until 24 weeks, but 4-D ultrasound has revealed some babies opening their eyes as early as 18 weeks. It's dark, of course, so there's nothing to see. But even if there were light, the eyes don't work this early. It's just the first sign of the blinking reflex. The foetus, which has been growing for 19 weeks, is now halfway through her journey towards birth. The roughly mapped-out baby has grown to 18 centimetres long

and is now taking on an incredible level of detail. She even has her very own fingerprints. MAN: Get a 3-D picture - just perfect - for one minute. ULTRASOUND WARBLES Most mothers will have a more detailed second scan around now which will survey the anatomy of the foetus and measure the rate of growth since the last scan. Coming on now.

Wow, it's a nice baby... These scans are performed for medical reasons only and help to predict possible complications. 4-D scans are especially good for diagnosing a cleft palate. But doctors have discovered a beneficial role the scans can play in developing a bond between the baby and her parents. There's the arms, going down to the sides. See that? WOMAN: Yeah. And now the baby's kneeling. And now the baby's kneeling. You see that? Yeah. Research has shown that seeing your baby's face and expression while it's still inside the womb can be an intense experience. And such early bonding can provide an important boost to the baby's development once it's born and to the long-term relationship between the child and her parents. And that's the arms there.

After six months of pregnancy, at the end of the second trimester, everything has developed and is functioning as it will in the fully-grown baby.

It's all there - just very small and immature. In the next phase, she will embark on one of the most dramatic challenges of her time in the womb -

the development of the senses.

The foetus is six months old now and has reached a major landmark.

Though barely longer than her father's hand, it is possible that she could survive outside the cradle of the womb. She'd still need extensive care,

but 24 weeks is currently regarded as the earliest that a baby can be born and still have a good chance of surviving.

Exceptionally, a few babies live when born as young as 22 weeks.

But any baby that is born prematurely faces an increased risk of brain damage, with nearly half of all babies born before 26 weeks developing disabilities or learning difficulties. The big problem is the lungs, which are barely capable at this feeble age of taking enough oxygen into the bloodstream to keep the baby alive.

For most babies, it's time to lie back and relax and look forward to the third trimester where they can put on some fat and learn how to work their bodies.

The mother is becoming increasingly aware of movements made by the foetus. Her abdomen will be growing and she's likely to be feeling better now

than at any time throughout her pregnancy and at her most energetic and active. She'll be past the effects of morning sickness and the foetus is not yet big enough to cause the kind of discomfort she will feel at the end of pregnancy. WATER BUBBLES LOUDLY From 24 weeks, or six months, From 24 weeks, or six months, the foetus enters one of the most exciting and dramatic periods of development. This is the time when she receives her first stimulation from the world beyond as her senses flicker into life. Most of the sense organs - ears, nose, tastebuds and the nerves that respond to touch - are now mature.

Her brain is being bombarded by signals from these sensory cells and it must begin to interpret this overload of sensation. Throughout her life, her senses will be her key to the world beyond. They will allow her to develop a sense of self, to interact with others, to explore and to learn.

The new generation of 4-D ultrasound scans are continually providing fresh insight into the behaviour of the growing foetus. The technology is advancing. And as the experience of practitioners evolves, the expanding wealth of imagery sheds new light on the invisible world inside the womb. In this image, we can clearly see a 24-week-old foetus sticking out her tongue. No-one knows exactly why, but we do know that her mouth is full of tastebuds. She could be tasting the amniotic fluid.

A foetus's mouth and nose are permanently filled with amniotic fluid that we know can carry the tastes and smells of the mother's food.

Strong flavours will easily pass through the placenta into the baby's bloodstream and will eventually be passed out into the amniotic fluid, and the baby can get an early taste of her mother's cooking. Taste and smell are closely linked. Taste is a very limited sense. It only tells you if food is sweet, sour, salty or bitter.

Its main purpose is to make sure we don't eat anything poisonous. To identify more complex flavours like garlic, onion, chicken, herbs, we actually use our sense of smell - a much more sophisticated sense. Very strong spices even stimulate pain receptors in the mouth.

A developed sense of taste and smell could help the baby take her first sips of breast milk, once she's born.

Just like the amniotic fluid, breast milk will contain a similar selection of tastes and smells from the mother's food. If the newborn baby is already familiar with these flavours and likes the taste, this may encourage her to feed. This scan shows a 24-week-old foetus opening and closing her eyes. Although the eyes are fully formed by halfway through the pregnancy five weeks ago, seeing is the one sense a foetus can't experience until she's born.

It's too dark in the womb.

It is possible that some very bright light could penetrate into the uterus - direct sunlight, for instance - and the foetus may be able to detect a faint glow. But the uterus wall is so thick - buried under a layer of skin and fat - that most of the time, the foetus evolves in total darkness.

There may be nothing to see, but opening and closing in this way

helps the foetus develop the blinking reflex - a reflex that stays with us for life, protecting our eyes from foreign objects, keeping them moist and shielding them from bright light. At 25 weeks, the eyes are so intricate that even the eyelashes have grown. But there is one detail that may not fully develop, however much time the foetus spends inside the womb - the colour of the eyes.

Some pigments need light to form properly and the baby's eyes may change colour during the first months of life. Babies of Asian or African descent will usually be born with dark brown or dark grey eyes that mature to deep brown or black. A Caucasian baby will almost always have blue eyes in the womb, even if they're destined to become green or brown. Geneticists used to believe that one gene determined the colour of the eyes,

but new research has shown that several genes are responsible and it's impossible to tell just from looking at the parents' eyes what colour the baby's eyes will be.

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LIQUID BUBBLES, MUFFLED CHATTER Perhaps the most keenly developed of all the foetal senses is hearing. HEART BEATS, MUFFLED CHATTER, WHOOSHING The foetus may be completely surrounded by amniotic fluid, but because sound travels through fluid about four times faster than it does in air, she has plenty to hear. MUFFLED CHEERING AND APPLAUSE The first sounds the foetus heard as her ears started picking up vibrations at 13 weeks were the gurgles and rumbles made by the mother's body. SLURPING, BUBBLING GURGLING A succession of hiccups, burps, bubbles, sloshes and slurps will mark the passage of food, liquid and air in, out and through the maze of passages and tubes just inches from the baby's ears. HEART BEATS THUD, GURGLING The foetus, too, makes her own noises as she kicks and swishes in the amniotic fluid. She will also hear the competing thuds of heartbeats -

her own, racing at twice the speed of her mother's, both her constant companions through her time in the womb. The foetus can also hear noises from the world outside - conversations, loud noises and music.

The walls of the womb, together with the abdomen, act as a filter to most of the high frequencies. All sounds will reach the foetus distorted, but higher sounds will be more muffled. Only the lower bass notes of a piece of music will have much impact. MUFFLED FEMALE VOICE Voices will sound distorted too. Vowels are generally lower in pitch than consonants, so the foetus will just hear the melody of speech without the percussion of consonants. MUFFLED FEMALE VOICE MOTHER: That's not like her at all. The sound of the mother's voice is different from any other since it travels directly through the fluids of the body. Oh! (Chuckles) This may help the baby develop the very different kind of relationship it has with its mother from anyone else. DISTORTED FEMALE VOICE Excellent. Good luck! See you later. 'Bye! MAN: Hey, Clara, give us your hand. Other voices, like the father's, must pass through air then fluid and may not cut through the general background noise. WAVES CRASH, MUFFLED MALE VOICE MALE DOCTOR: See her little face there? The loudest sound a foetus will ever hear may come during an ultrasound scan. It's impossible to hear the actual ultrasound waves - they're at far too high a frequency to affect the human ear... ..but the ultrasound could cause secondary waves in the amniotic fluid that the baby can hear. GENTLE HIGH-PITCHED WARBLING To produce finely detailed images, ultrasound probes fire a rapid succession of pulses, each lasting less than one millionth of a second. The rapid switching on and off of these pulses can cause waves in the fluid which would sound like a high-pitched tapping sound. GENTLE HIGH-PITCHED TAPPING If the probe were pointed directly at the baby's ear, it could sound as loud as a subway train. HIGH-PITCHED OSCILLATING RUMBLE

In normal circumstances, there is no need for the scanning probe to go anywhere near the ear. But if for any reason the baby was at all unhappy, she could easily wriggle away from the sound. Doctors have observed foetuses grimace and frown, just like in this 4-D scan, as they manipulate the foetus through the mother's abdomen.

Along with the expansion of the senses comes the development of pain. During the final trimester, the foetus must prepare for life outside the womb - away from her comforting cocoon and its built-in life support. Many of the crucial tricks and skills she will need to survive on the outside are innate reflexes that she will develop in the womb. From the 26th week, babies spend about 90% of their time asleep. And when they sleep, nothing will wake them. BLENDER WHIRRS

For the other 10% of the time, they are awake and alert, ready for whatever might happen next.

They may react to sudden sounds with a startle reflex, flinging arms and legs out to the side. The startle reflex is thought to have originated at a time when we were more at risk of being eaten. A sudden noise or touch from a predator will trigger the reflex and cause the arms to fling out to the side in what may be an attempt at self-preservation. This may not be so relevant to our lives today, but other reflexes are crucial to survival after birth. In this 4-D image, the foetus is swallowing amniotic fluid, and during this trimester she will swallow up to half a litre of fluid every day. By swallowing amniotic fluid, the foetus helps maintain the fluid balance in the womb. It also helps her digestive system develop properly. But from the moment she is born and the cord is cut, she will need to have perfected the art of taking food from her mouth to her stomach. (Gurgles) (Coughs) Alongside swallowing, one of the most important reflexes to have perfected before birth is sucking. Anything vaguely nipple-sized that comes close to her mouth will trigger her attempts at the sucking reflex. This foetus, aged 25 weeks, first sucked its thumb at about 11 weeks, at which time it may already have begun to develop a lifelong preference for one hand or the other. Ultrasound scans have shown that as soon as thumb sucking begins, a foetus tends to show a clear preference for either the left or right thumb. This left or right-handedness will stay with it for life - something previously thought to kick in only when a child is three or four years old. At 26 weeks, the foetus measures 25cm from head to bottom. She's growing fast, and as she moves through the third trimester towards birth, the foetus will triple her weight and double her length. There will continue to be dramatic growth in the brain and nervous system and the foetus will create her first memory.

By week 26, it may just be possible to hear the foetal heartbeat by putting your ear against the mother's abdomen. Is she kicking?

Um... HEARTBEAT THUDS RAPIDLY

It's quite loud. The foetus's heart beats about twice as fast as her mother's. Monitoring the baby's heartbeat gives a good indication of her general condition. It's more of a vibration, though. MUFFLED VOICES I can feel her.

GENTLE HEARTBEAT The mother's heart rate and blood pressure are directly affected by her emotional state. If she's calm, her heart will slow down and her blood pressure will drop. CAR HORN TOOTS, ENGINES ROAR If she's tense and stressed,

her heart will beat faster and her blood pressure will rise. JACKHAMMER DRILLS Although the foetus has her own separate blood supply, these increases in heart rate and blood pressure are easily passed through the placenta

and have a direct impact on the baby. JACKHAMMER DRILLS, ENGINES WHINE

It takes a while for the effects to filter through, but when the mother is recovering from the impact of stress and her heart rate is returning to normal, her baby's heart begins to race as the physiological effects of stress creep through the placenta. HEARTBEAT QUICKENS In the short-term, stress in the mother can lead to low birth weight or premature birth. But it's also possible that a mother's prolonged anxiety and stress can be passed on,

establishing a tendency for stress in the child and making her more likely to develop chronic health problems, heart disease, diabetes as an adult. It can even have a harmful effect on the child's mental development in the early years of her life. By now, the mother will be feeling her baby move every day.

Usually this will be the foetus kicking or pushing. But sometimes she may feel the regular twitch of her baby's hiccups. Hiccups are an involuntary sudden contraction of the diaphragm. Why foetuses hiccup is a bit of a mystery. One theory says

it's a reflex that may help a baby latch onto a nipple and feed. The spasm of a foetus's hiccup is strong enough to feel. But unlike our own hiccups, it makes no sound at all. The sound of an adult hiccup is made by the sudden rush of air that is stopped by the closure of our vocal cords.

But of course, in the foetus's lungs, there is no air and so no hiccup sound. The last of the major organs to form are the lungs.

The lungs don't function during the time in the womb. All the foetus's oxygen is delivered from the mother's blood via the placenta. Inside the foetus's lungs, the branching network of tubes is filled with amniotic fluid during the entire time in the womb. And the tiny air sacs that will extract oxygen from the air remain closed. But the foetus still makes breathing movements with her lungs and diaphragm. This helps the chest muscles practise, ready to expand and fill the lungs with air the moment the baby is born. Most foetuses that reach 26 weeks

will make it through to birth with no further problem - putting on weight, exercising reflexes as well as their new senses. But sometimes things do go wrong. This 26-week-old foetus has developed a hole in his diaphragm, the membrane separating the lungs from the abdomen. Baby's facing the completely wrong position. It's not a problem now. But it means his intestines will grow into the lung cavity. This will stop the lungs developing properly,

and when he is born, the baby will almost certainly be unable to breathe and will die. Professor Kypros Nicolaides is a world-renowned pioneer of foetal surgery at King's College Hospital in London. He has developed a technique to block the windpipe of the foetus with an inflatable bladder. This forces the intestines back where they belong and allows the lungs to develop properly. The procedure is done with keyhole surgery, using a fetoscope to operate on the baby inside the womb. A fetoscope is a long narrow tube filled with fibre-optic filaments. Light travels down one set of fibres to illuminate inside the uterus

and is passed back out to a camera so the surgeon can see what he's doing. It also carries the delicate instruments to conduct the operation. The first step is to inject an anaesthetic into the foetus to stop it moving. The mother is awake during the entire procedure with only a local anaesthetic to numb her. A general anaesthetic would be too harmful for the baby. Professor Nicolaides then inserts the fetoscope through an incision in the mother's abdomen into the amniotic cavity.

Once he has safely reached the foetus, he gently pushes the fetoscope into the mouth and down the back of the throat. So here... MAN: Here. And there. Then we discover... There. So that is the epiglottis on the right.

Once inside the trachea, he inflates a tiny balloon that traps fluid inside the lungs. As the foetus grows, the lungs produce more fluid which stimulates the lung tissue to grow and expand, forcing the intestines out of the chest cavity. The balloon is left in place for two months to give the lungs time to mature. The procedure is then repeated and the balloon is removed in time for what everyone hopes will be a normal birth. Since this operation to treat babies with this defect has been available, it has increased their chance of survival by 50%. Every day, Frank Booth runs up and down this building. But Frank is no ordinary runner. He's a Sun-Herald City to Surf runner. (Pants) That's why he'll be racing to a newsagent to get his free City to Surf 35th anniversary bag. Make sure you get yours, only with 'The Sun-Herald', tomorrow. At 28 weeks, the baby

is over two-thirds of the way through her time in the womb and is gaining weight fast as she lays down a layer of fat under her skin. Her senses are buzzing and her cerebral cortex has matured enough to support consciousness. Over the next four weeks, her nervous system will become as advanced as a newborn baby's.

She is becoming aware of the world around her and for the first time, her brain is beginning to create memory. WOMAN: Oh, what - really screaming? The foetus will have spent so much time listening to her mother's voice she will have become familiar with its rhythms. What are you doing going to a mother-and-toddler group? With this constant exposure, she'll absorb enough of these patterns to recognise and even respond to her mother's voice. Oh... No, I thought she was, though. Researchers analysing the cries of newborns found they already contain some of the rhythms and patterns of their mother's speech.

Yeah, you'll be fine. MOTHER'S MUFFLED VOICE The foetus can now hear, taste, smell and touch. She is likely to have turned head-down in the womb. She is getting ready for birth. For the mother, this change could be marked by some painful kicks straight in the ribs. LAIDBACK POP SONG PLAYS The type of music a baby's exposed to can alter her mood. Fast music will stimulate and excite her. THUMPING ROCK SONG PLAYS Music that is closest to the natural sounds and rhythms of the human voice, such as classical or choral music, will have a sedating, calming effect. CHORAL MUSIC PLAYS

CHEERFUL POP SONG PLAYS If she hears the same music over and over again, she may even be able to remember it.

At 33 weeks, the foetus may recognise a particular piece of music and can even jump in time to it.

In one study, babies were repeatedly exposed to a particular TV soap opera theme during pregnancy.

(Baby wails) After birth, when the same music was played to them, these babies became alert, relaxed and would stop crying. Babies that had not been exposed to the music in the womb would show no reaction at all to the same piece of music. For the researchers conducting the experiment, this was evidence of long-term memory at work before the baby is born. Hey diddle diddle, the cat and the fiddle, the cow jumped over the moon.

The little dog laughed to see such fun and the dish ran away with the spoon. Hey diddle diddle, the cat and the fiddle, the cow jumped over the moon. The little dog laughed... In a similar experiment, mothers would repeat a children's rhyme each day during the final month. ..and the dish ran away with the spoon. The little dog laughed to see such fun... ..the cow jumped over the moon... At the end of the experiment, a recurrent decrease in foetal heart rate showed that the foetus had become familiar with this particular rhyme as opposed to similar rhymes they had not heard.

(Muffled) The little dog laughed to see such fun and the dish ran away with the spoon. Hey diddle diddle, the cat and the fiddle, the cow jumped over the moon. Some scientists argue that there is very little difference between the brain of a newborn baby and that of a 32-week-old foetus. The cow jumped over... Where once it seemed that the mental development of a baby began at birth, now it appears birth could be a relatively insignificant event

in developmental terms. She may have to support herself after birth, but as for the process of thinking, learning and remembering, she will already have been hard at work for three months and her brain will continue to grow at the same rate for the next year. The final phase of pregnancy is a demanding one for the mother. Many women feel uncomfortable during the last couple of months. The weight of the baby, together with pressure on the spine and a battle for space, can all cause back and legs to ache.

She may be feeling anxious about the birth and is likely to feel breathless as her lungs struggle to absorb 20% more oxygen than normal. One of the things revealed by the 4-D scans is the fact that babies have REM - rapid eye movement sleep, a period of sleep where the eyes flick around behind the eyelids.

Later in life, we know this is an indication of dreaming. This gentle flicker of an eye could be a sign that the foetus, still with a month to go before even being born, is already dreaming. Though, with such little life experience, it's hard to imagine what they dream about - playing with their feet, perhaps, or the gurgling of their mother's stomach.

(Muffled) And the dish ran away with the spoon... MUFFLED MALE VOICE But why? In adulthood, dreaming plays a vital role in allowing us to make sense of events around us and develop strategies to deal with the world. In a foetus, dreaming - however simple the dreams - may be the crucial process that stimulates the brain to grow and develop. MUFFLED CAR HORN BLARES, SEAGULLS SQUAWK Sleep deprivation in a foetus or a newborn baby can seriously impair brain development.

In just over eight months, the brain has grown approximately 100 billion neurons with 100 trillion connections. The brain and head have grown as big as they can in the womb and still be able to squeeze through the mother's pelvis. The foetus could quite happily survive

if born anytime from about 35 weeks,

even without much medical help, although the longer she stays inside, the healthier she will be at birth. The mother is likely to be getting increasingly uncomfortable. Having begun as a single cell, the baby is now cramped and heavy. She is also a considerable drain on her mother and in putting on fat is taking more resources than the mother can provide. It's time to emerge.

The countdown is on. It's impossible to tell when the baby will be born exactly. Only 5% of babies are born on their due date. The rest can emerge any time two weeks either side of that. The mother is kept guessing and waiting for signs - the first contraction of the uterus

or the breaking waters as the amniotic sack ruptures.

Nobody knows exactly what initiates labour. But it's the baby's lungs, together with the placenta, that are the key to the timing.

When the lungs are mature, they secrete a protein into the amniotic fluid which alters the placenta's production of hormones. It slows the release of progesterone and triggers the release of a new hormone, oxytocin, which kick-starts the contractions of the uterus wall, and labour begins. Oxytocin also inhibits memory, and may have a role in helping women to forget the pain of birth and to bond with their new babies. During the first stage of labour, the baby's head is locked in the bottom of the uterus and is bearing down on the cervix, the barrier between the uterus and the vagina. The last thing to pass through the cervix was a tiny sperm, 38 weeks ago.

Now it must stretch 10cm wide to allow the baby's head - its largest part - to pass through. (Woman moans) MIDWIFE: Wonderful. Slow down. Slow your breathing down. The pain's gone. For the mother, the pain of birth can be eased if she gives birth standing up, sitting, or squatting, rather than lying on her back. This can also speed up the first stage of labour and reduce the likelihood of medical intervention or a caesarean. Labour is also painful and stressful for the baby. The squashing of the umbilical cord can easily constrict the supply of oxygen. To help the baby cope, her body releases large quantities of adrenaline to keep her heart pumping fast enough. RAPID HEARTBEAT Adrenaline also helps prepare the lungs for the lifetime of work they're about to begin. Once the cervix is fully opened, the second stage of labour - the actual delivery - begins. (Woman grunts) With each contraction of the uterus, the baby is pushed further through the cervix and the vagina,

until eventually her head is just visible. Baby's head's just coming... The contractions are only minutes apart now, and after each one, the midwife encourages the mother to push down hard and help squeeze the baby out. MIDWIFE: Bigger push. Bit more for me. Wonderful. (Woman screams) Keep going. Bit more. Bit more. (Woman groans) Good girl. Good girl. Breathe now, breathe. Breathe, breathe, breathe.

Good girl. Here's your baby! (Woman groans) The baby's head.

Here we go. Just checking for the cord, darling. Next contraction we'll have this baby out, OK? MUFFLED VOICE CONTINUES MAN: Next contraction we should have the shoulders and everything else. Think he's got a hand here as well. He's brought a hand out with him. You got a contraction yet, darling? OK, give me a big push. MUFFLED VOICE AND GROANS Here we go! (Woman screams) Here you are! Oh, thank God! Hello! And he's... (Baby cries and chokes) It's a beautiful baby! As soon as the baby is delivered, her lungs drain of fluid and air rushes in, expanding the air sacs, and, in an instant, begin extracting oxygen to keep the baby alive. (Baby continues to cry) Stand up for me, darling. We'll come round and just support her neck. What we've got to do is pop him through here. Here we go. (Baby continues to cry) Wonderful. (Man chuckles) (Cries) All her vital life systems are now working independently and the umbilical cord can be cut. Just in between there, Dad. It's a bit chompy, so just...big cut.

There we go. (Speaks softly) (Baby cries) The placenta is now redundant, and in the third stage of labour it detaches from the uterus wall and follows the baby out through the vagina. After growing painstakingly inside her womb for nine months, the baby finally comes face-to-face with her mother. The sweet smile seen inside the womb has gone now,

as the baby is thrust into a noisy, bright world and starts to feel uncomfortable sensations such as cold and hunger for the first time.

The smile won't be seen again until she's at least four weeks old. (Cries) Each year, across the world, around 130 million women go through the complex cycle of pregnancy and birth. Our increasingly sophisticated understanding of the process has drastically reduced the risks. Ironically, it is the one thing that allows us this understanding - our large brains - that is mainly responsible for the difficulties of human childbirth in the first place. Most mammals with smaller brains and heads have a much easier time squeezing out their offspring. Their infants are also more advanced than our helpless babies, often able to walk, feed, and escape from predators immediately after birth. For a human baby to be this advanced, its mother would have to bear a 21-month pregnancy and then give birth to a toddler. Having been cocooned for nine months, this little girl is now on her own. Her parents will feed her and keep her warm, but for the first time, her body must keep itself alive. She had gone from egg to embryo to foetus to trillions of cells of newborn baby. Her birth marks the beginning of her journey in the world, but she's already travelled an incredible path

during her nine-month odyssey in the womb. Protected by her mother and following her own unique genetic blueprint, she has grown a face, arms, eyes, legs. She has a brain and nervous system to control her body, stomach and intestines to digest food, and a heart to pump blood. She has learnt to breathe, to hear, to feed, to remember, and to tell her parents when she's hungry, tired, happy or in pain. All before even being born. And now she is ready to face the world. Supertext Captions by the Australian Caption Centre www.auscap.com.au