To investigate the joint effect of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on children's cognitive development. We recruited 1685 mother-child pairs from the Ma'anshan Birth Cohort in China. Pre-pregnancy BMI and GWG were calculated based on the height and weights measured at multiple antenatal checkups. Children's cognition was assessed by Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition. Poisson regression model was used to analyze the association between maternal pre-pregnancy BMI and children's cognitive dimensions under different GWG categories. Women with overweight or obese before pregnancy were more likely to obtain excessive GWG. When women had excessive GWG, pre-pregnancy overweight was associated with low children's PSI (OR = 1.69, 95%CI: 1.02-2.81) and pre-pregnancy obesity was related to poor VCI in children (OR = 3.71, 95%CI: 1.49-9.22), after adjusting for potential confounders. In pre-pregnancy underweight mothers, adequate GWG reduced the risk of below-average VSI in children (OR = 0.22, 95%CI: 0.05-0.92), but excessive GWG was related to low FSIQ in children (OR = 2.53, 95%CI: 1.34-4.76). In women with excessive GWG, maternal pre-pregnancy BMI displays an inverted U-shape association with children's cognition. Moreover, adequate GWG in women with pre-pregnancy underweight was beneficial for children's cognition.
Keywords: body mass index; children; cognitive development; gestational weight gain; pre-pregnancy; public health.