Serum FSH level is lower in dysovulating than in ovulating non-PCOS obese women, independently of body mass index.

Objectives: The prevalence of ovulation disorder (OD) is 3-fold higher in obese than normal-weight women. Most ODs are associated with concomitant polycystic ovary syndrome (PCOS), but obesity by itself can cause OD, through mechanisms that remain poorly documented. The literature on obese non-PCOS women with OD is sparse. The aim of the present study was to analyze a population of obese non-PCOS women with OD to shed further light on the mechanism of ovulation disorder.
Material and Methods: This retrospective observational study of infertile obese women without PCOS compared a control group without OD (n=45) to a study group with OD (n=30) (OD group). Clinical, hormonal, and ultrasound characteristics were collected between cycle days 2 and 5. Women older than 37 years and women with PCOM (polycystic ovarian morphology) or hormonal disorder were excluded.
Results: Body mass index (BMI) was significantly higher in the OD group, as were waist circumference and insulin and leptin serum levels. Conversely, serum follicle stimulating hormone (FSH) levels were significantly lower. After adjustment for BMI, only serum FSH level remained significantly different between the 2 groups. Discriminant analysis suggested that FSH may have a much stronger effect on OD than BMI.
Conclusion: Low serum FSH level may contribute to OD in some obese women, independently of BMI. The pathophysiological mechanism of this finding and its impact on therapeutic strategies must be clarified.
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