Many factors influence a child’s growth and development, including parenting styles, environmental exposures, socioeconomic status, and maternal health. Maternal obesity, in particular, drives inflammatory, hormonal, and metabolic dysfunction that may adversely affect a developing fetus. Findings from a new study indicate that boys born to obese women perform poorly in measures of motor skills and intelligence compared to children born to healthy weight women.

The study involved 368 children born to low-income African American or Dominican women living in the United States. The children underwent motor skill and intelligence testing at the ages of 3 and 7 years, respectively. The women were weighed before and during their pregnancies.

Boys born to women who were overweight or obese during pregnancy scored poorly on motor skills tests at age 3. Similarly, boys whose mothers were overweight or obese during pregnancy scored 5 or more points lower on intelligence tests, compared to boys whose mothers were a healthy weight. Girls did not exhibit differences in motor skills or intelligence. Interestingly, a nurturing home environment modulated some, but not all, of the negative effects of maternal obesity on development.

Although this was a prospective study and causation cannot be established, these findings point to the importance of maternal nutritional status before and during pregnancy. Unfortunately, this study did not control for important confounders such as diet during pregnancy or whether mothers breastfed their sons. Breastfeeding has been linked to intelligence in children.

It is noteworthy that the negative effects of maternal obesity were only found in boys and not girls. Other studies have shown that exposure to lead or fluoride in-utero has a negative effect on intelligence in boys. It seems as though boys are particularly vulnerable during fetal development.

• Link to full study.