Estrogen triggers the thickening of the endometrium.
Estrogens are a class of hormones that are essential for women's healthy sexual and reproductive development. They are sex hormones as well. The majority of estrogen hormones are produced by a woman's ovaries, however minor amounts are also produced in modest amounts by the adrenal glands and fat cells.
Estrogen influences the reproductive system, the urinary tract, the heart and blood vessels, the bones, the breasts, the skin, the hair, the mucous membranes, the pelvic muscles and the brain in addition to controlling the monthly cycle. When oestrogen levels rise, secondary sexual features like pubic and armpit hair also begin to sprout.
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