Study links maternal obesity during pregnancy to behavioral problems in boys

July 14, 2017

Pregnant woman weighing

A study from researchers at the UC Berkeley School of Public Health has uncovered a possible association between mothers who were obese when entering pregnancy and childhood neurodevelopmental problems of their sons.

The findings were published in the July 2017 issue of American Journal of Preventive Medicine.

"The results suggest that early intervention with women to attain healthy weights before they become pregnant is critical to their health and the health of their future children," said the study’s senior investigator Professor Barbara Abrams.

The study corroborates other recent research that has linked neurodevelopmental and psychiatric problems, like ADHD, and maternal obesity. Researchers looked specifically at the body-mass index (BMI) of mothers when they entered pregnancy. Researchers also found possible connections to other problems in children, such as cognitive deficits and internalizing issues such as depression.

To investigate the correlation between pre-pregnancy obesity and behavioral issues among school age children, the researchers used data from Nearly 5,000 female participants in the U.S. National Longitudinal Survey of Youth 1979 (NLSY79), and included race and gender in their analysis. Behavioral problems were assessed every two years for children aged 4-14 years using maternal report of the Behavior Problems Index (BPI), a widely used 28-item questionnaire, to determine whether they exhibited specific behaviors in the past three months. Because early puberty is a time when behavioral problems tend to emerge, this study focused on children aged 9-11 years.

Approximately 65 percent of the mothers were normal weight, 8 percent underweight, and 10 percent obese, of whom 3.5 percent were BMI 35 or higher. Underweight women were younger, less likely to be married, and had the lowest education, income, and Armed Forces Qualifying Test scores.

The study showed that boys whose mothers entered pregnancy obese were at higher risk for behavior problems at ages 9-11 years. Data indicated that the heavier mothers were when they entered pregnancy, the higher the risk for behavioral problems to develop in their sons. Boys whose mothers were underweight pre-pregnancy also showed a higher risk for behavior problems. The study did not show the same effects in girls, and there were no differences for race.

"Past research looking at a variety of exposures during pregnancy (ranging from stress to chemicals) has shown that boys tend to be more vulnerable to these exposures in utero than girls," said Associate Professor Juliana Deardorff, one of the study’s investigators. "Our study extends this work to maternal obesity."

The study is one of the first to document how maternal obesity affects genders, according to Deardorff. Additionally, the study is one of a small number to show that both excessive weight and low weight for women entering pregnancy may be problematic.

"Future research should examine whether the gender differences reported here for ages 9-11 years persist into adolescence or shift as children get older,” she said.