In a premenopausal woman, which estrogen is predominantly produced?

• A. Estradiol
• B. Estrone
• C. Estriol
• D. Estrone sulfate

Answer: (A)

During the reproductive years, estradiol is the predominant estrogen produced by the ovaries. It is synthesized mainly by the granulosa cells of developing follicles under FSH stimulation and rises to peak around ovulation, driving endometrial proliferation in the cycle. This ovarian source makes estradiol the main circulating estrogen in premenopausal women, with levels fluctuating across the cycle.

In contrast, estrone becomes the principal estrogen after menopause, when ovarian production declines and peripheral tissues (especially adipose tissue) convert androgens to estrogens mainly as estrone. Estriol is more prominent during pregnancy, reflecting placental and fetal contributions, and estrone sulfate serves as a circulating reservoir that can be converted back to active estrogens but is not the main estrogen in premenopause.