Maternal pre-pregnancy overweight and infertility in sons and daughters: a cohort study.

INTRODUCTION Overweight and obesity in pregnancy is increasing worldwide and may harm the developing fetus including its future reproductive health. We therefore studied the association between maternal overweight and obesity in fetal life and infertility in adulthood. No studies have previously assessed this association. MATERIAL AND METHODS We performed a cohort study with 9,232 adult sons and daughters, whose mothers were enrolled in the Danish Healthy Habits for Two cohort during pregnancy in 1984-87. Participants were sons and daughters, followed in the Danish In-Vitro-Fertilization-Register and Danish National Patient Register until February 2018 for diagnoses of infertility. RESULTS In total, 1,203 (13 %) sons and daughters were born to mothers with a body mass index (BMI) above 25 kg/m2 , and 871 (9.4 %) participants were identified as being infertile during follow-up. Sons of overweight mothers had slightly increased odds of infertility compared to sons of mothers with normal body weight (BMI: 18.5-24.9 kg/m2 , adjusted odds ratio 1.4 (95 % CI 1.0-1.9). Cubic spline analyses with continuous BMI levels, showed increasing odds with higher levels of BMI, however, for BMI>29 kg/m2 the CIs were too wide to draw conclusions. No association between maternal overweight and infertility was found among daughters (adjusted odds ratio 0.9 (95% CI 0.7-1.2)). CONCLUSIONS Sons born to overweight mothers had higher odds of infertility compared to sons of normal weight mothers. No association between maternal overweight and infertility was observed in daughters. Prevention of overweight during pregnancy may be an important tool to preserve fecundity in future generations.