HOUSTON – Second-trimester maternal obesity was associated with lower scores in offspring on neurocognitive tests in early childhood.
This observation initially came as an unexpected finding, a byproduct of a case-control study set up for another purpose. But the disturbing finding, particularly in light of the ongoing obesity epidemic, led researchers to take a second look at the issue using an entirely separate data set. Those findings were confirmatory, Wendy Y. Craig, Ph.D., of the Foundation for Blood Research in Scarborough, Maine, reported at the annual meeting of the Endocrine Society.
The initial study involved a cohort of 101 children who underwent neurocognitive testing at age 2 years using the Bayley Scales of Infant Development, Third Edition (BSID-III). Their mothers, who were pregnant during 2004-2006, had a 30% prevalence of second trimester obesity.
The mean BSID-III cognitive and motor scores didn’t differ significantly between offspring of mothers who were normal-weight, overweight, or obese in pregnancy. However, mean BSID-III language scores averaged 110.6 in the children of normal-weight mothers, 107.2 in those whose mothers were overweight, and 98.0 in children born to women with second trimester obesity; that difference was highly statistically significant (P = .009).
Moreover, after adjustment for potential confounders in a multivariate regression analysis, it was apparent that the proportion of children with a BSID-III composite score below 85 rose with increasing maternal weight in pregnancy. The rate was 3.1% in the offspring of normal weight mothers, 7.7% in kids whose mothers were overweight, and 33.3% in those whose mothers were obese.
The second study included 118 children tested at age 8 years using the Wechsler Intelligence Scale for Children (WISC-III). Their mothers had been pregnant during 1987-1990, or 15 years earlier than in the first study population, and their prevalence of second-trimester obesity in that earlier, leaner era was a mere 10%.
The mean unadjusted WISC-III performance IQ score for children whose mothers were obese in pregnancy was 10.7 points lower than children of normal-weight mothers. Similarly, the full scale IQ and verbal subscale scores were lower by an average of 9.2 and 6.4 points, respectively.
"Although we cannot rule out the possibility that other covariates not measured in this study were responsible for the observed relationships, an independent effect of maternal obesity on the child’s early neurocognitive development deserves further investigation," Dr. Craig concluded.
All participants in both studies were recruited from the Maine statewide pregnancy project. The studies were supported by the National Institute of Child Health and Human Development, the Thrasher Fund, and Knoll Pharmaceuticals. Dr. Craig reported having no financial conflicts.