Development of Zygote and Fetus (II)

The blood of the fetus and the mother do not mix. The placenta secretes hormones which controls embryo development and also transfers between the embryo and the mother through simple diffusion.

Show a diagram of fetus at 12 weeks

The fetus continues to develop. All the major organs of the baby form from the 1st to 12th week. The organs of the embryo develop and grow in size and this makes the stomach of the mother grow larger because the uterus of the mother enlarges. The fetus spends about 40 weeks to fully develop in the uterus. This is called gestation period and it is the time from fertilization to birth.

Show a picture of a full grown pregnancy

After the development of the fetus, the baby is fully developed. All the organs in the baby have been formed. The baby has taken its rightful position in the womb to be born. The head has been positioned at the cervix for safe delivery.