Look who is growing there
The first 8 weeks
One week after fertilisation, the embryo will attach itself to the uterine wall. The embryo is connected here with the circulation of the mother and can start to grow. Up to the end of the 4th week, some blood vessels and the preliminary stages of bone marrow and brain tissue are formed. In the fifth week, the heart begins to beat and transports oxygen to the brain that is now growing too. The heart beats up to 120 times a minute. For comparison: The mother’s heart beats 60 – 80 times a minute on average. The little body starts to take on a shape. First the arms and hands and then legs and feet. The face gets eyes and a mouth, a nose, ears, and lips
9. to 12th week
Now the decision is made as to whether it is going to be a boy or a girl. That has long been decided in terms of genetics, but nature has provided the genes for both genitalia and leaves it up to the hormones to decide. In this phase, all organs are completed; hands and feet react to contact, the embryo can furrow its brow and turn its head. In the 12th week, the embryo has grown to a length of 9 cm from crown to rump (this is called the CRL measurement), and it weighs about 50 grams. Hands and elbows move separately from one another, the fingers grasp for the umbilical cord, the legs kick, and the embryo bends its knees to turn.
13th to 16th week
In the 13th to 16th week, the embryo becomes a foetus. The body develops systematically, the central nervous system coordinates the control of movements and reflexes like stretching, grasping or sucking. The heart beats up to 160 times a minute. The kidneys of the fetus increasingly take on the formation of amniotic fluid from the 14/15th week. The foetus takes small sips of the fluid and excretes them germ-free. In the 16th week, the foetus is about 14 cm and weighs about 180 grams.
17th to 20th week
In the 17th to 20th week, the foetus is about 19 cm in length and weighs approximately 450 grams. The senses develop. Pain, pressure, cold, and sounds are now perceptible and can also influence the further development.
21st to 24th week
In the 21st to 24th week, the body is almost completely formed and the mother can feel this very clearly: The foetus trains its movements and develops its muscles. The sabaceous glands produce vernix caseosa, which protects the skin from the amniotic fluid. The first taste buds begin to function – the foetus can distinguish between sweet and sour. At the same time, the lungs develop their function, allowing the foetus to switch to air breathing with the help of breathing aid in about the 24th week. The hair begins to grow, the eyes open. The foetus is about 23 cm in the 24th week and weighs about 650 grams.
25th to 28th week
In the 25th to 28th week, the fine details develop. Eyelashes and eyebrows grow; yawning, sucking its thumb and making a fist belong to the repertoire of skills now. In the 28th week, the foetus is about 27 cm long (CRL) and weighs around 1,350 grams. The space in the stomach is becoming more confined as the foetus starts to build up fatty tissue. The contact to the parents is becoming more and more important. The foetus recognises voices and tender stroking on the mother’s stomach.
29th to the 32nd week
From the 29th to the 32nd week, the body builds up further fat deposits so it is well prepared for its start to life. In the 32nd week, the foetus is around 30 cm in length and weighs about 2,200 grams.
33rd to 36th week
In the 33rd to 36th week, the foetus develops its own sleep-wakeup rhythm. Since it does not have much room anymore, it periodically bumps against the wall of the stomach, which the mother is clearly able to feel. The little body continues to build up fat, but reduces the production of vernix caseosa. The foetus is about 34 cm in the 36th week and weighs about 2,800 grams.
From the 37th week
Up to the time of birth, the baby will put on about 500 grams, the soft down on the body has almost disappeared and the remaining vernix caseosa is absorbed by the skin and nurtures it. Now it is time for the foetus to position itself for birth: Normally, the foetus pushes its head forward into the pelvic outlet. It braces its legs in the diaphragm area. The contractions of the mother help the baby through the tight opening in the birth canal until it reaches the opening and states: “Hello world, here I am!”