estradiol

Estradiol is the strongest naturally occurring estrogen, a steroid hormone that is central to sexual and reproductive development, especially in females. It is produced mainly by the ovaries during the reproductive years, with smaller amounts coming from the adrenal glands, fat tissue, and, during pregnancy, the placenta. From puberty onward, it helps guide changes such as breast development, the menstrual cycle, and the maturation of the reproductive system.

Throughout the reproductive years, estradiol levels rise and fall during the menstrual cycle. They usually peak before ovulation and help prepare the uterine lining for a possible pregnancy. During pregnancy, estradiol supports changes in the body that help maintain the pregnancy and support fetal development. Even after menopause, when ovarian production drops, estradiol still matters because estrogen levels are tied to bone strength, and they also affect other body systems.

But estradiol is not only relevant to females. Males also produce it, usually in much smaller amounts, and it still contributes to bone health, sexual function, and brain function.

In medicine, estradiol is used in several ways. It may be prescribed in hormone therapy, including treatment for menopause symptoms such as hot flashes, and it is also used in some gender-affirming care. Some hormonal medicines also include forms of estrogen related to estradiol. Doctors measure estradiol levels with blood tests when checking fertility, menstrual problems, menopause, or ovarian function. It is a small molecule with wide effects across the body, which is why it matters not only in reproductive health but in overall health as well.