Impact of obesity on ovulatory functions in polycystic ovarian syndrome

Abstract

Background Indeed, the impact of obesity on female infertility is a topic of increasing importance in modern gynecological practice and extensive research is needed to reach well-defined guidelines. In this study, the effect of obesity on ovulatory functions in polycystic ovarian syndrome (PCOS) was evaluated in 80 PCOS patients attending the infertility outpatient clinic of Kasr Al-Aini hospital. Patients and methods A total of 80 PCOS patients were selected according to a restricted inclusion and exclusion criteria from Kasr Al-Aini infertility clinic during the period from July 2011 to March 2012; they were divided into three groups according to BMI: group A included 38 patients with BMI less than 30 kg/m2, group B included 24 patients with a BMI of 30–35 kg/m2, and group C included 18 patients with a BMI of 35–40 kg/m2. Ovulatory function inthe three groups was evaluated by folliculometry and evaluation of day 21 progesterone levels. Basal hormonal profile on day 2 of the cycle [follicle-stimulating hormone, luteinizing hormone (LH), ethinyl estradiol, prolactin (PRL), and thyroid-stimulating hormone levels] was also evaluated and statistically analyzed. Results The results showed significant differences in the basal levels of LH and PRL (P<0.05) between the three groups; there was an inverse correlation between obesity and basal LH levels. The PRL level was also significantly higher in the nonobese groups. There was no significant difference in the basal level of follicle-stimulating hormone, ethinyl estradiol, and thyroid-stimulating hormone. With respect to ovulatory functions, the nonobese group showed better ovulatory performance especially when monitored in terms of day 21 progesterone levels (18.4% compared with 5.5% in the morbidly obese group). Conclusion Obesity in PCOS seems to increase the risk for anovulation, most probably through the disruption of the hypothalamo-pituitary axis by hyperandrogenism and/or insulin resistance. Leptin may play a role through its direct effect on folliculogenesis. Weight reduction in patients with PCOS may improve ovulatory performance. Monitoring ovulation by folliculometry alone may not reflect accurate ovarian response, and addition of assessment of day 21 progesterone levels should be considered to improve the evaluation. Further studies and randomized control trials are needed to justify this conclusion.