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Biological Plausibility is the most important component in classifying a risk factor as causal; in spite of evidence by meta-analysis the mechanism of action should be able to be explained biologically. Obesity, according to our understanding, has dual mechanisms of action on obstetrical and gynecological abnormalities, e.g.:
-In endometrial cancer and ovarian cancer, it is because of excess estrogens (estrone, specifically) production by adipose tissue, which in excess is carcinogenic.
-while in gestational diabetes and polycystic ovarian syndrome, it is because of androgens. Both insulin and leutinizing hormone (excess of both these hormones ocurrs in PCOS) stimulate androgen production by the ovarian theca cell. As a result, affected ovaries secrete elevated levels of testosterone and androstenedione. Specifically, elevated free testosterone levels are noted in 70 to 80 percent of women with PCOS, and 25 to 65 percent exhibit elevated levels of DHEAS). In turn, elevated androstenedione levels contribute to an increase in estrone levels through peripheral conversion of androgens to estrogens by aromatase (Williams gynaecology, 3rd addition).
No competing interests
30 October 2017
Akshun Jani, Jugal Kishore and Neeta Kumar, KK Jani