What is the most common risk factor for PCOS?

• A. Endometriosis
• B. Obesity
• C. Nulliparity
• D. Family history

Answer: (B)

Obesity is the most common risk factor for PCOS because excess adiposity drives insulin resistance, which is central to the syndrome. When the body becomes insulin resistant, there’s more circulating insulin (hyperinsulinemia). This stimulates the ovaries to produce more androgens and also lowers SHBG, increasing the amount of free testosterone. The result is disrupted follicle development and ovulation, along with hyperandrogenic symptoms like irregular menses and hirsutism. Weight gain tends to worsen these hormonal issues, while even modest weight loss can improve ovulatory function and metabolic health.

Endometriosis is a separate gynecologic condition and isn’t considered a risk factor for PCOS. Nulliparity isn’t a cause of PCOS; many women with PCOS are infertile due to anovulation, which can lead to nulliparity, but it’s not an initiating risk factor. Family history reflects genetic predisposition, which can be associated with PCOS, but obesity is more commonly observed and modifiable in affected individuals.