Menstruation and Pregnancy Hormones

Menstruation and Pregnancy Hormones



Rising levels of estrogen are responsible for the build up of the uterine lining (endometrium). This build up of the lining gets the uterus ready to accept a fertilized egg. As the cycle continues, and no pregnancy occurs, the levels of estrogen decrease. Decreasing estrogen loosens the support for the built up lining and helps to make it separate, and prepare for menses.

Follicle-stimulating hormone


This hormone is made by the pituitary gland. Its purpose is to get a follicle ready for ovulation. Every month between 3 and 30 follicles are ripened for ovulation but usually only one continues to grow and eventually ruptures and releases an egg during ovulation.

Luteinizing hormone


This is the hormone that makes the egg (follicle) release from the ovary. This hormone is involved in the process of ovulation – the time in the menstrual cycle when the follicle ruptures and releases the egg from the ovary.



This hormone is released by the ruptured follicle (one that has released an egg). After the egg is released from the follicle, the follicle closes and becomes a corpus luteum. The corpus luteum secretes increasing amounts of progesterone. This rise in the level of progesterone typically causes a rise in body temperature. If no pregnancy occurs, the levels of progesterone falls and this along with the decreasing amount of estrogen, helps the built up lining of the uterus to separate and for menstruation to begin.

Human chorionic gonadotropin (hcg)


Manufactured by the cells of the newly developing placenta within days after the fertilized egg implants in the uterine lining and gets the hormonal ball rolling by stimulating the corpus luteum to pump out even more estrogen and progesterone. HCG is found in the urine and the blood. It is the cause of morning sickness and queasiness queasiness. Many researchers say it is no coincidence that morning sickness usually subsides around the same time that hCG levels start to decrease, which is around the beginning of the second trimester, when the placenta takes over production of estrogen and progesterone. Also responsible for voiding all the time.