Many hormone levels are affected in the body during pregnancy. Several hormones play major roles during pregnancy. These are:
Human chorionic gonadotropin hormone (hCG). This hormone is made only during pregnancy. It is made almost exclusively in the placenta. HCG hormone levels found in the mother's blood and urine rise a lot during the first trimester. They may play a part in the nausea and vomiting often linked to pregnancy.
Human placental lactogen (hPL). This hormone is also known as human chorionic somatomammotropin. It is made by the placenta. It gives nutrition to the fetus. It also stimulates milk glands in the breasts for breastfeeding.
Estrogen. This group of hormones helps develop the female sexual traits. It is normally formed in the ovaries. It is also made by the placenta during pregnancy to help maintain a healthy pregnancy.
Progesterone. This hormone is made by the ovaries and by the placenta during pregnancy. It stimulates the thickening of the uterine lining for implantation of a fertilized egg.