Body mass index and delayed conception: A European multicenter study on infertility and subfecundity

Obesity has become a health problem in affluent societies, but few studies have investigated its effect on subfertility. Previous studies were based o n select groups of women, focused mainly on ovulatory dysfunctions, and yie lded controversial results. The authors evaluated the effect of body mass i ndex on delayed conception by using a European population-based survey of p regnant women from five countries. Delayed conception was defined as a time to pregnancy that exceeded 9.5 months of unprotected intercourse. During 1 992, 4,035 pregnant women from well-defined geographic areas were recruited consecutively at antenatal clinics or hospitals after at least 20 weeks of gestation. For women smokers, after adjustment for sociodemographic, biolo gic, and lifestyle-related factors, there was a strong association between obesity (body mass index of greater than or equal to 30 kg/m(2)) and delaye d conception (odds ratio = 11.54, 95% confidence interval: 3.68, 36.15) and also an increased risk for women whose body mass index was <20 kg/m(2) (od ds ratio = 1.70; 95% confidence interval: 1.01, 2.83). The same analysis co nducted for women nonsmokers showed no association. The authors concluded t hat for women who achieve a clinically detectable pregnancy, those who are underweight or obese require a longer time to conceive only if they also sm oke.