Estrogen, the hormone most closely associated with women, actually represents several specialized female hormones that play various roles at various stages throughout a woman’s life. Estrogens are one of five groups of steroid hormones that control all body functions.
Estrogen and the Female Reproductive Cycle
Once a fertilized egg becomes a fetus, sex differences begin to develop and are guided by the most prominent of the sex hormones: estrogens for females, androgens for males. During fetal development, estrogen influences development of the female reproductive system and other female characteristics.
Once a girl reaches puberty, estrogen production accelerates, triggering the growth of breasts and the onset of menstruation as the girl reaches sexual maturity.
During the menstrual cycle, the ovary expels an egg at ovulation. This egg produces progesterone that causes the lining of the uterus to thicken. The uterine lining thickens to prepare it for implantation of an egg should fertilization occur.
If fertilization occurs, estrogen and progesterone work together to protect and promote the pregnancy and stop further ovulation until after childbirth. As the placenta develops, it produces estriol, a form of estrogen unique to pregnancy.
If fertilization does not occur, estrogen and progesterone levels drop dramatically, triggering the onset of menstruation, a process that expels the unfertilized egg and thickened uterine lining.
At the end of her reproductive life, estrogen levels drop and a woman begins a process called perimenopause, a cessation of the menstrual cycle that can last several years. Menopause signals the end of estrogen production for reproductive purposes.
Other Functions of Estrogen
The estrogens are directly related to female reproduction but they are vital to other body systems as well:
- Sexual Performance — Estrogen helps keep the female reproductive system in optimum health for conception and pregnancy and enhances a woman’s sexual pleasure. Some women experience vaginal dryness and other discomforts that hinder sexual performance once menopause begins.
- Skeletal Structure — The female body’s ability to metabolize calcium, vitamin D, and other nutrients vital for strong bones is enhanced by estrogen. Women risk osteoporosis, a thinning of the bones, when estrogen levels begin to drop during perimenopause.
- Cardiovascular System — Women are significantly less likely than men to develop heart disease during reproductive years. This estrogen-related cardiovascular protection ends when estrogen production declines with menopause.
- Urinary Health — Women with low estrogen levels, as in menopause, often experience a thinning of the urethra which makes them more prone to urinary tract and kidney infections.