The Subcutaneous Abdominal Fat and Not the Intra-Abdominal Fat Compartment Is Associated With Anovulation in Women With Obesity and Infertility

Abstract

A marked increase in anovulation occurs in overweight and obese women. Rates of conception decline both in spontaneous conception and in assisted reproduction with the accumulation of fat around the waist and trunk in women, with a waist-to-hip ratio >0.8, independent of body weight. Although several studies have investigated the contribution of intra-abdominal fat (IAF) and subcutaneous abdominal fat (SAF) compartments to anovulation and reduced conception, their differential effect on anovulation is unclear. This study investigated the individual contribution of IAF and SAF to anovulation in women with obesity and infertility. The participants were 57 volunteers at a mean age of 30 and a mean body mass index (BMI) of 37.7, who were stratified on the basis of ovulatory status into anovulatory (n = 40) and ovulatory (n = 17) groups. The distribution of body fat was measured using anthropometric assessment (body weight, BMI, waist circumference, and waist-to-hip ratio), dual-energy x-ray absorptiometry, and single-sliced abdominal computed tomography scan. Multiple logistic regression analysis was used to determine the independent contribution of IAF, SAF, and other variables to anovulation after adjustment for BMI, testosterone, and fasting insulin. The data showed that anovulatory obese women had a significantly higher waist circumference (113 ± 11 cm vs. 104 ± 9 cm; P < 0.01), abdominal fat (4.4 ± 1.3 kg vs. 3.5 ± 0.9 kg; P < 0.05), and trunk fat (23.0 ± 5.3 kg vs. 19.1 ± 4.2 kg; P < 0.01) on dual-energy x-ray absorptiometry scan compared with the ovulatory obese women, despite nonsignificant differences in BMI, age, and total fat mass. Anovulatory obese women had significantly more SAF than ovulatory women (992 ± 198 vs. 864 ± 146 cm 3 ; P < 0.05). In contrast, IAF made no contribution to anovulatory status. There was no significant difference between anovulatory and ovulatory obese women in the volume of IAF on single-sliced abdominal computed tomography (203 ± 56 vs.195 ± 71 cm 3 ; P < 0.65). Only trunk fat, abdominal fat, and SAF had an independent association with anovulation after adjustment for variables. These findings indicate a differential contribution of SAF and IAF to abdominal fat in anovulatory obese infertile women. SAF, and not the IAF, is significantly increased in anovulatory women compared with the ovulatory controls. SAF accumulation around the abdomen and trunk is associated with anovulation.