Hormones are the chemicals within the body that send signals to set off various functions. Rising and falling levels of different hormones are essential in reproduction, pregnancy and birth. Here are the main ones involved in having a baby:
Estrogen and progesterone – Prior to pregnancy, these are produced in the ovaries and they tell the lining of the uterus to thicken during each menstrual cycle. And they tell the lining to cast itself off if pregnancy does not occur. Once an egg is fertilized, increasing levels of estrogen and progesterone prevent ovulation from occurring again.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) – These hormones are made by the pituitary gland, located at the base of the brain. FSH causes an egg to ripen in one of the ovaries and LH triggers the egg’s release.
Gonadotropin-releasing hormone (GnRH) – Also produced in the pituitary gland, this hormone signals the production of FSH and LH.
Human chorionic gonadotropin (hCG) – This hormone is produced by the fertilized and dividing/growing egg. It tells the body to increase estrogen and progesterone production. This is the hormone that pregnancy tests look for in a urine sample (approx. 6-12 days after fertilization).
Rising and lowering hormone levels are essential for the process of reproduction and the maintenance of pregnancy. What’s important is that the individual hormones rise and fall in a coordinated dance with masterful timing. Pretty impressive stuff.