Overall and central adiposity was associated with decreased fertility among pregnancy planners, while vigorous physical activity was associated with improved fertility among overweight and obese women only, and moderate physical activity with improved fertility among all women. This according to a North American preconception cohort study of 2,062 females pregnancy planners when they self-reported pregnancy. Researchers found:
• Relative to body mass index (BMI) 18.5 to 24 kg/m2, fecundability ratios (FRs) for BMI <18.5, 25 to 29, 30 to 34, 35 to 39, 40 to 44, and ≥45 kg/m2 were 1.05, 1.01, 0.98, 0.78, 0.61, and 0.42, respectively.
• Reduced fecundability was observed among women with the largest waist-to-hip ratios and waist circumferences.
• Tendency to gain weight in the chest/shoulders (FR=0.63) and waist/stomach (FR=0.90), relative to hips/thighs, was associated with lower fecundability.
• Moderate physical activity was associated with increased fecundability, but there was no dose-response relations.
• Among overweight/obese women, fecundability was 27% higher for vigorous physical activity of ≥5 vs <1 hr/wk.
Citation: McKinnon CJ, Hatch EE, Rothman KJ, et al. Body mass index, physical activity and fecundability in a North American preconception cohort study. [Published online ahead of print April 25, 2016]. Fertil Steril. doi:10.1016/j.fertnstert.2016.04.011.