Body size affects measures of ovarian reserve in late reproductive age women.

Objective: To examine the association between obesity and serum and ultrasound measures of ovarian reserve in late reproductive age women.

Design: Cross-sectional study of 36 healthy women, ages 40 to 52 years. Women were recruited in a 1:1 ratio of normal weight (body mass index <25) to obese women (body mass index >or=30). Early follicular phase blood draw, anthropometric measurements, and a transvaginal ultrasonography were performed. Outcome measures were serum antimullerian hormone, inhibin B, estradiol, follicle-stimulating hormone, ultrasound ovarian volume, and antral follicle count.

Results: Mean antral follicle count was 7.6 for normal weight and 6.3 for obese women (P = 0.35). Proportions of normal weight (17%) versus obese women (22%) with antral follicle count less than 4 were similar. Ovarian volumes did not differ by body size. In adjusted models, antimullerian hormone levels in obese women were 77% lower on average than those in normal weight women (P = 0.02). Inhibin B levels were 24% lower in obese women compared with normal weight women (P = 0.08). Follicle-stimulating hormone and estradiol were not associated with body mass index.

Conclusions: Although antral follicle count did not differ by body size, antimullerian hormone was lower in obese compared with normal weight late reproductive age women. These data suggest that lower antimullerian hormone levels in obese late reproductive age women result from physiologic processes other than decreased ovarian reserve.