Objectives: To examine the association between maternal prepregnancy weight and child neurodevelopment, and the effect of gestational weight gain.
Methods: Using the U.S. Collaborative Perinatal Project data, 1959–76, a total of 30 212 women with a calculable prepregnancy body mass index (BMI) and gestational weight gain, and term singleton children followed up for more than 7 years were included in this study. Intelligence quotient (IQ) was measured at 7 years of age by Wechsler Intelligence Scales.
Results: Maternal prepregnancy BMI displayed inverted U-shaped associations with child IQ after adjustment for maternal age, maternal education levels, maternal race, marital status, socioeconomic status, smoking during pregnancy, parity and study center. Women with BMI at around 20 kg/m2 appeared to have the highest offspring IQ scores. After controlling for familial factors in the siblings’ sample, maternal obesity (BMI ≥30.0 kg/m2) was associated with lower Full-scale IQ (adjusted ß = −2.0, 95% confidence interval −3.5 to −0.5), and Verbal scale IQ (adjusted ß = −2.5, 95% confidence interval −4.0 to −1.0), using BMI of 18.5–24.9 kg/m2 as the reference category. Compared with children born to normal-weight women who gained 21–25 lb. during pregnancy, those born to obese women who gained more than 40 lb. had 6.5 points deficit in IQ after adjustment for potential confounders.
Conclusions: Maternal prepregnancy obesity was associated with lower child IQ, and excessive weight gain accelerated the association. With obesity rising steadily, these results appear to raise serious public health concerns.