The impact of prepregnancy obesity on children's cognitive test scores.

To examine the association between maternal prepregnancy obesity and cognitive test scores of children at early primary school age. A descriptive observational design was used. Study subjects consist of 3,412 US children aged 60-83 months from the National Longitudinal Survey of Youth 1979 Mother and Child Survey. Cognitive test scores using the Peabody Individual Achievement Test reading recognition and mathematics tests were used as the outcomes of interest. Association with maternal prepregnancy obesity was examined using the ordinary least square regression controlling for intrauterine, family background, maternal and child factors. Children of obese women had 3 points (0.23 SD units) lower peabody individual achievement test (PIAT) reading recognition score (p = 0.007), and 2 points (0.16 SD units) lower PIAT mathematics scores (p < 0.0001), holding all other factors constant. As expected, cognitive test score was associated with stimulating home environment (reading: β = 0.15, p < 0.0001, and math: β = 0.15, p < 0.0001), household income (reading: β = 0.03, p = 0.02 and math: β = 0.04, p = 0.004), maternal education (reading: β = 0.42, p = 0.0005, and math: β = 0.32, p = 0.008), and maternal cognitive skills (reading: β = 0.11, p < 0.0001, and math: β = 0.09, p < 0.0001). There was a significant association between maternal prepregnancy obesity and child cognitive test scores that could not be explained by other intrauterine, family background, maternal, and child factors. Children who live in disadvantaged postnatal environments may be most affected by the effects of maternal prepregnancy obesity. Replications of the current study using different cohorts are warranted to confirm the association between maternal prepregnancy obesity and child cognitive test scores.