(HealthDay News) – Maternal pre-pregnancy body mass index (BMI) is negatively associated with children’s cognitive performance at ages 5 and 7, although the overall effect size is modest, according to research published online Dec. 10 in Pediatrics.

Emre Basatemur, MBBS, of University College London, and colleagues used data from the Millennium Cohort study to prospectively evaluate the association between maternal pre-pregnancy BMI and cognitive performance for 19,517 children at 5 and 7 years of age. General cognitive ability was identified using individual test scores from standardized cognitive assessments.

The researchers found that a mother’s pre-pregnancy BMI correlated negatively with cognitive performance in their children at ages 5 (P=0.0069) and 7 (P<0.0001). Although statistically significant, the overall effect size was modest, with a 10-point increase in maternal BMI correlating with a decrease of one-tenth of a standard deviation in cognitive performance at age 7.

“By using data from a large, contemporary national birth cohort, we found that maternal pre-pregnancy BMI is negatively associated with children’s cognitive performance, even after adjusting for various socio-demographic confounders and children’s BMI. The relationship appears to become stronger as the children get older,” the authors write. “Although our study design does not permit any inferences of causation, a suboptimal intrauterine environment in obesity may have direct effects on the developing fetal brain.”

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