What is estriol?

Estriol is one of the three main estrogens (estradiol and estrone are the other two) produced by the human body. Estriol differs from estradiol and estrone because it is only produced in significant amounts during pregnancy.

Estriol is made by the placenta from 16­-hydroxydehydroepiandrosterone sulfate (16­-OH DHEAS), an androgen steroid made in the fetal liver and adrenal glands. Estriol is virtually undetectable in the body until pregnancy, when its levels drastically increase. It is thought that the hormone suppresses the immune system so that women’s bodies do not treat the fetus as foreign or harmful. Levels of estriol in nonpregnant women do not change significantly after menopause and resemble those observed in men. 

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.