The Inside Story
The Inside Story
The development of the baby can be divided into three specific periods of three months each, together making nine months, which we call trimesters.
The first trimester (1-3 months)
By the end of the first three months the baby is about 3.5 inches (nearly 18 cm.) long. The vital organs and the limbs are fully formed but not sufficiently developed. The amniotic sac contains about 3.5 ounces (nearly 100c.c.) of amniotic fluid and the has plenty of room to move about, although the mother will not yet feel the movements. The heart is beating, the eyes, though closed, are in position. The facial features are properly formed and the ears are in place on the sides of the head. The sex organs are developed so that the baby has a male or female identity.
The swallows the amniotic fluid, most of which is used by its body, and it produces drops of sterile urine. The amniotic fluid is constantly refreshed by the amniotic sac. As the baby is not breathing, it does not choke. It gets its oxygen from the mother’s blood-stream through the umbilical cord.
The second trimester (4-6 months)
By the end of the second trimester the baby is about 14 inches (35.5 cm) long, roughly the length of its mother’s fist and forearm, and weighs about two pounds, or a little less than one kilogram. At the start of the second trimester, or from the, fifth month onwards, the mother begins to feel movements of the foetus, and the pregnancy begins ‘to show’. The foetus can now smile and suck its thumb. At the ends of the fingers and toes ridges develop, giving the baby a unique identity of finger-prints.
The trunk and legs of the lengthen and the head no longer looks too large for the rest of its body. Eyelashes and eyebrows appear, although the eyes remain closed until the end of this trimester.
The skin begins to grow a coat of fine downy hair called lanugo, which is shed before or shortly after birth. During this period the baby also develops a whitish greasy coating called vernix from the oil secreted from its skin and dead skin cells.
The foetus now swallows the amniotic fluid every day and returns it to the amniotic sac through urination. The amniotic fluid is recycled every hour, when one third of it is absorbed into the mother’s bloodstream and replaced with fresh fluid secreted from the amniotic sac.
The third trimester (7-9 months)
During the last three months the baby gains weight, and slowly grows to reach right up to the mother’s breastbone. As the foetus becomes large it can no longer move freely as before, since it gets cramped for space. So now instead of movements of the foetus, the mother feels it kicks and pokes.
More about the foetus
During this trimester the baby stores up protein to build muscles, calcium for its bones, iron for its red blood cells, fat to insulate it against changes in temperature after birth.
By the end of the seventh month the foetus’s brain matures to be able to cope with breathing and swallowing. Thumb sucking is now resorted to more frequently. If born at this stage the baby has a lesser chance of survival.
By the end of the eighth month the foetus looks quite like what it will look at birth. Although the lungs are not yet fully operational, the baby born at this stage has a good chance of survival.
It is during the last trimester that the foetus’s eyes open. The senses undergo their greatest development at this stage. The hair on the head grows and finger nails and toe nails develop.
During the ninth month the foetus generally turns head down in the womb. About two weeks before birth, it descends about two inches, settling into the mother’s pelvic bones. This is called lightening, engagement or ‘fixing’ of the head.