What is estrogen and why is it important?
Estrogens are a group of sex hormones in people with ovaries. They include estrone (E1), estradiol (E2), and estriol (E3), and they’re produced by the ovaries, the adrenal gland, and the placenta during pregnancy.
At puberty, estrogen leads to the growth of breasts, pubic and underarm hair, and kick off (and later help control) our menstrual cycles.
Estrogen also plays a role in keeping our cholesterol levels in check, maintaining our bone health, and producing hormones that affect our brains, hearts, and skin (among other parts of our bodies). (Source)