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Female Hormones 101

From puberty to menopause, a woman’s reproductive cycle is guided by the rise and fall of four main classes of hormones: two sex hormones produced primarily by the ovaries and two stimulating hormones released from the brain.

In women, estrogen and progesterone are the two main sex hormones. Although many women think of estrogen as one hormone, estrogen actually flows through our bodies in three forms. Estradiol, or E2, is the main type of estrogen produced by our ovaries and is dominant during our reproductive years. Estriol (E3) becomes more prominent during pregnancy, and estrone (E1) is found in greatest quantities after menopause. Progesterone is the sex hormone that complements estrogen, rising and falling throughout each month during the menstrual cycle.

In addition to these sex hormones, a woman’s body is also guided by hormones that are released from the pituitary, a small gland in the brain. The main players here are follicle stimulating hormone (FSH) and luteinizing hormone (LH), and both play important roles in the female body along with estrogen and progesterone. Like the notes in a symphony, these four hormones rise and fall each month in a carefully orchestrated fashion to prepare the body for possible conception. During a typical menstrual cycle we’ll see the following:

Day 1-5: Day 1 is the onset of menstrual bleeding as the lining of the uterus sheds. The estrogen levels fall and FSH rises. As the name implies, FSH stimulates one of our ovarian follicles, containing eggs, to develop and then release large amounts of estrogen.

Day 6-14: As the estrogen rises sharply, the uterine lining thickens to prepare for possible implantation of a fertilized (by sperm) egg. The high estrogen also sends messages to the brain and suppresses the release of FSH. By mid-cycle (about day 14) the estrogen helps stimulate a sudden release of luteinizing hormone (LH), accompanied by a brief rise in body temperature, meaning that ovulation will occur very soon. The follicle ruptures, releasing an egg into a fallopian tube where it may be fertilized by a sperm.

Day 14-28: After the egg is released, the follicle becomes known as a corpus luteum, now secreting progesterone. The progesterone and estrogen levels rise. If the egg has been fertilized, it produces human chorionic gonadotrophin (HCG) and levels stay high. If the egg is not fertilized, the estrogen and progesterone levels will begin to fall, causing the uterine lining to shed, and the beginning of menstruation occurs. As a woman ages, the ovaries slow down in their production of hormones, leading to the symptoms associated with menopause.

So what happens when we get older and experience menopause? Click here to read more about menopause.

Special thanks to:

Dr. Melinda Ring, Medical Director of the Center for Integrative Medicine at Northwestern Memorial Hospital and Assistant Professor in the Department of Medicine at Northwestern University's Feinberg School of Medicine for her contributions.

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