21 Weeks Pregnant
Your baby is about 26.7 cms in length from head to heal (10.51 inches) and weighs about 360 grams (12.70 oz).
How tall your baby will be at birth is controlled almost entirely by their genetic program, but how much weight they now gain depends upon the health of the placenta and on your available stores. From about this stage onwards your baby will weigh more than the placenta (which, until now, was heavier than your baby). The placenta will keep growing throughout pregnancy, but not as fast as your baby.
Around this time, the baby becomes covered in a very fine, soft hair called lanugo. The purpose of this isn't known, but it's thought that it may be to keep the baby at the right temperature. The lanugo usually disappears before birth.
22 Weeks Pregnant
Your baby is about 27.8 cms in length from head to heal (10.94 inches) and weighs about 430 grams (15.17 oz).
Daily cycles may now start to emerge in your baby’s activity. You might observe patterns of sleeping and waking which is a sign of increasing maturity. Your baby’s pattern of day and night will probably not be the same as yours, as your movements during the day tend to lull your baby to sleep and your stillness at night provides opportunities to move.
The lungs continue to make breathing movements, they are now more frequent and for longer periods than before, often at night rather than during the day. However, your baby’s lungs are by no means mature. They rely on the placenta for oxygen and removal of waste carbon dioxide, and will do so until birth.
23 Weeks Pregnant
Your baby is about 28.9 cms in length from head to heal (11.38 inches) and weighs about 501 grams (1.10 lbs).
As your baby gains weight their body becomes more rounded. Some of the fat stores they are building are special ‘brown fat’, which not only provides additional insulation, but produces heat when burnt, enabling the baby to regulate its temperature from birth. The special brown fat develops in just three areas: at the nape of the neck, around the kidneys and behind the breastbone. Your baby is also developing a layer of ordinary white fat which will give a cushioning and insulating padding. The skin is now thicker but has no pigment as yet and so babies of all races look very similar at this point.
24 Weeks Pregnant
Your baby is about 30 cms in length from head to heal (11.81 inches) and weighs about 600 grams (1.32 lbs).
Although your baby is still very immature, they do have a chance of survival if they had to be born now. This is due mostly to the stage of development of the baby’s lungs. The care that can now be given in neonatal (baby) 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.
What we have learnt from very premature babies is that at this age the vocal cords can function, prematurely born babies can give a weak cry. We know that babies of this age show stress responses under conditions which might cause pain.