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Estrogen is a group of hormones that play an essential role in the growth and development of female sexual characteristics and the reproductive system. The three major naturally occurring estrogens in women are:
- Estrone
- Estradiol
- Estriol
What does estrogen do?
Estrogen has many important functions in the female body. Some of the key things estrogen does include:
- Stimulates development of female secondary sexual characteristics during puberty - breasts, pubic hair, etc.
- Regulates the menstrual cycle
- Thickens the endometrium (uterine lining) to prepare for potential pregnancy
- Maintains bone strength and density
- Regulates cholesterol levels
Estrogen levels fluctuate throughout a woman's menstrual cycle. They rise during the pre-ovulatory phase to prepare for ovulation, peak just before ovulation, and decline during menstruation.
Where does estrogen come from?
In biological females, the main sources of estrogen are:
- Ovaries - Secrete high levels of estradiol, the dominant estrogen
- Adrenal glands - Produce lower levels of estrone and estradiol
- Fat tissue - Converts male hormones into estrogens through aromatization
During pregnancy, the placenta produces high quantities of estriol. Estriol helps support fetal development and prevents immune reactions against the fetus.
Estrogen deficiency
Estrogen deficiency can occur due to primary ovarian insufficiency, menopause, premature ovarian failure, or hypothalamic amenorrhea. Common symptoms include:
- Hot flashes
- Vaginal dryness
- Mood changes
- Sleep problems
Estrogen levels also decline with age. Low estrogen post-menopause increases risks for heart disease and osteoporosis in older women.
Hormone replacement therapy containing estrogen may help alleviate menopausal symptoms and side effects from low estrogen levels in some women.
In summary, estrogen is an important group of sex hormones involved in female growth and reproduction. Maintaining healthy estrogen levels is essential for physical, mental, and emotional well-being in girls and women.