What happens after fertilization?

The fertilized egg begins to divide as it travels down the fallopian tube towards the womb. By the time it enters the womb, it has divided into a ball of about 100 cells. It settles on the wall of the womb and sinks into the surface, becoming firmly fixed. At this point, the female is pregnant.

For the first eight weeks of pregnancy, the developing egg is called an embryo. A liquid-filled bag develops around the embryo to protect it. By the fourth week of pregnancy, the embryo is the size of a grain of rice. It has a head and a tail and the beginning of limbs, and its tiny heart begins to beat. The placenta is the embryo's life-support system. It is a red, flattened organ that becomes deeply embedded in the wall of the womb. The placenta extracts food substances from the mother's blood and passes waste material from the embryo back to the mother for disposal. The placenta is connected to the developing baby by a thick umbilical cord, which contains large blood vessels.

After the first eight weeks of pregnancy, the developing baby is called a fetus. by now, all of its major organs have formed and it is growing at a very fast rate. By the 16th week, the fetus starts to move about and by the 20th week it may already have eyebrows and fingernails. It weighs approximately 350 grams.

At the 26th week, the baby is big enough to survive if it is born prematurely. It weighs about 1.5 kg and from now on it increases in weight ready to be born. Soon the bay turns over into a head-down position ready for the birth, which usually takes place at around the 38th week.