What Is the Connection between Estrogen and FSH?

The connection between estrogen and follicle stimulating hormone (FSH) is that estrogen and FSH are both crucial parts of the ovarian cycle, which is the process by which a woman ovulates; FSH ignites the ovarian cycle, which in turn ignites estrogen production. Another link between estrogen and FSH is that they are both hormones, which means they are regulating chemicals that guide physiological functions in the body. Estrogen is a sex hormone while FSH is a gonadotropin. Their roles are vastly different despite both being within the realm of female sexual reproduction. FSH’s role is to control all developmental phases of the ovaries from birth through menopause; estrogen’s role is to primarily control the woman’s menstrual cycle.

Both estrogen and FSH are necessary components of menstruation and pregnancy. FSH triggers single egg production and releases every 28 days, making it necessary for a woman to create a uterine lining that can cushion a fertilized ovum or be expelled as reproductive waste during menstruation. Estrogen causes the growth and thickening of that uterine lining, which is also known as the endometrium. Without estrogen and FSH, female reproduction would not be possible.

Each monthly ovarian cycle starts when FSH is released by the pituitary gland, triggering the formation of an ovum, or egg, in one of the woman’s ovaries. During ovum development, the egg follicle forms first; this follicle, which will eventually be the protective sac around the egg until it matures and is released into the fallopian tubes for ovulation, is what secretes the female hormone estrogen. Specifically, the follicle emits a form of estrogen known as estradiol. While other tissues in the body can produce low levels of estrogen, egg follicles regulated by FSH are responsible for the major levels of estrogen production in the female body.

During the first 14 days of the 28-day menstrual cycle, levels of estrogen and FSH are at their highest as the follicle develops over several days. On the 14th day after the egg has matured, it is released from the follicle and travels to the Fallopian tube. The left-behind follicle, called corpus luteum, continues to secrete small quantities of estrogen until the 28th day of the cycle when the entire process starts over again after FSH renews its activity.

Onset of menopause has drastic effects on both estrogen and FSH. Aged ovaries cease to be receptive to FSH and ignore signals to produce egg follicles. This, in turn, results in a drop in estrogen production. Loss in estrogen can have detrimental effects on women, since, in addition to reproduction, estrogen aids in skin elasticity, mood balancing, and health of the vulva and other parts of the vagina. Many doctors, therefore, prescribe steroidal estrogen to replace concentrations of the hormone no longer naturally produced by the body.