The following information is taken from the NHS pregnancy care planner. The description of the baby’s development indicates how quickly the baby develops, and exposes how euphemistic the descriptions of abortion are. Note that the ages, unless otherwise indicated, are gestational i.e. refer not to the baby’s actual age but to the first day of the mother’s last menstrual period.
How your baby is growing: 0-8 weeks
Three weeks from the first day of your last menstrual period, the fertilised egg moves slowly along the fallopian tube towards the womb. The egg begins as one single cell. This cell divides again and again. By the time the egg reaches the womb it has become a mass of over 100 cells called an embryo, and is still growing. Once in the womb, the embryo burrows into the womb lining. This is called implantation.
In weeks four to five the embryo settles into the womb lining. The outer cells reach out like roots to link with the mother’s blood supply. The inner cells form into two and then later into three layers. Each of these layers will grow to be different parts of the baby’s body. One layer becomes the brain and nervous system, the skin, eyes and ears. Another layer becomes the lungs, stomach and gut. The third layer becomes the heart, blood, muscles and bones.
The fifth week is the time of the first missed period, when most women are only just beginning to think they may be pregnant. Yet already the baby’s nervous system is starting to develop. A groove forms in the top layer of cells. The cells fold up and round to make a hollow tube called the neural tube. This will become the baby’s brain and spinal cord, so the tube has a ‘head end’ and a ‘tail end’. Defects in this tube are the cause of spina bifida.
At the same time the heart is forming and the baby already has some of its own blood vessels. A string of these blood vessels connects baby and mother and will become the umbilical cord.
By weeks six to seven there is a large bulge where the heart is and a bump for the head because the brain is developing. The heart begins to beat and can be seen beating on an ultrasound scan. Dimples on the side of the head will become the ears and there are thickenings where the eyes will be. On the body, bumps are forming that will become muscles and bones, and small swellings called limb buds show where the arms and legs are growing. At seven weeks the embryo has grown to
about 10mm long from head to bottom. This measurement is called the ‘crown-rump length’.
How your baby is growing: 9-12 weeks
From about eight weeks on the baby is called a foetus, meaning ‘young one’. By now a face is slowly forming. The eyes are more obvious and have some colour in them. There is a mouth with a tongue. There are now the beginnings of hands and feet, with ridges where the fingers and toes will be. The major internal organs are all developing, i.e. the heart, brain, lungs, kidneys, liver and gut.
At nine weeks, the baby has grown to about 22mm long from head to bottom. Just 12 weeks after conception the foetus is fully formed. It has all its organs, muscles, limbs and bones, and its sex organs are well developed. From now on it has to grow and mature. The baby is already moving about but the movements cannot yet be felt.
How your baby is growing: 13-16 weeks
By about 14 weeks the heartbeat is strong and can be heard by using an ultrasound detector. The heartbeat is very fast, about twice as fast as a normal adult’s heartbeat. At 14 weeks the baby is about 85mm long from head to bottom. Your pregnancy may just be beginning to show, but this varies a lot from woman to woman.
How your baby is growing: 17-20 weeks
The baby is now growing quickly. The body grows bigger so that the head and body are more in proportion and the baby doesn’t look so top heavy. The face begins to look much more human and the hair is beginning to grow as well as eyebrows and eyelashes. The lines on the skin of the fingers are now formed, so the baby already has its own individual fingerprints. Finger and toenails are growing and the baby has a firm hand grip.
You will probably feel your baby move for the first time around now. At first you feel a fluttering or bubbling, or a very slight shifting movement, maybe a bit like indigestion. Later you can’t mistake the movements and you can even see the baby kicking about. Often you can guess which bump is a hand or a foot and so on.
How your baby is growing: 21-24 weeks
At about 22 weeks the baby becomes covered in a very fine, soft hair called lanugo. The purpose of this isn’t known, but it is thought that it may be to keep the baby at the right temperature. The lanugo disappears before birth, though sometimes just a little is left and disappears later.
At 24 weeks, the baby has a chance of survival if it is born. Most babies born before this time cannot live because their lungs and other vital organs are not developed enough. The care that can now be given in neonatal units means that more and more babies born early do survive. But for babies born at around this time there are increased risks of disability.
How your baby is growing: 29-32 weeks
The head-to-bottom length at 30 weeks is about 33cm. The baby is growing plumper so the skin, which was quite wrinkled before, is now smoother. Both the white, greasy vernix and the soft, furry lanugo begin to disappear. By about 32 weeks the baby is usually lying with its head pointing downwards, ready for birth.
How your baby is growing: 33-36 weeks
The baby’s brain and nervous system are now fully developed. Your baby’s bones are also starting to harden, even though the skull bones will stay soft and separated to make the journey through the birth canal easier. Baby boys’ testicles are now beginning to descend from the abdomen into the scrotum.
You may start noticing some signs of pre-labour. These can include Braxton Hicks contractions, which are small, practice contractions that last about 25 seconds. They should not be painful but may cause some discomfort.
How your baby is growing: 37-40 weeks
Some time before birth, the baby’s head may move down into the pelvis and is said to be ‘engaged’, but sometimes the baby’s head does not engage until labour has started. The amniotic fluid now turns into waste, called meconium, in the baby’s intestines, and the soft hair (lanugo) that covered your baby’s body is now almost all gone.
By week 40 your baby is ready to be born but don’t worry if nothing is happening as it is not unusual for pregnancies to continue to 42 or 43 weeks.
