Types and Fluctuation of Estrogen
Before a female reaches menopause, her body produces four different types of estrogen:
- Estrone (E1): Estrone is made in the ovaries. E1 production decreases during pregnancy and with menopause. It has weak effects on the body, including maintenance of bone health.5
- Estradiol (E2): Like E1, estradiol is made in the ovaries. It is the most prevalent estrogen in the body during the reproductive years. Its main job is to mature and maintain the reproductive system.6
- Estriol (E3): Estriol is present in small amounts in premenopausal women. It is the main estrogen produced during pregnancy and it is made by the placenta.7
- Estetrol (E4): This hormone is made by a growing fetus, and it is only produced during pregnancy.8
Estrogen levels can go up and down depending on the stage of life, menstrual cycle, pregnancy, and menopause.
Puberty
During puberty, the increased levels of sex hormones (primarily estrogen) result in physical changes, including the development of:
- Breasts
- Ovaries
- Uterus
- Vagina
During the 28-Day Cycle
During the menstrual cycle, estrogen levels fluctuate throughout the month. Secreted by the developing egg follicle, this hormone aids in thickening the endometrium for ovulation and possible pregnancy.9
Pregnancy
Estrogen levels increase steadily during pregnancy and reach their peak in the third trimester. During the second trimester, it plays a major role in the milk duct development that enlarges the breasts.
During Menopause
As you approach menopause, the ovaries begin to become physically smaller and begin to slow down their production of hormones, including estrogen and progesterone. After menopause, estrone is the only estrogen hormone that the body continues to produce, albeit in small amounts.