Is the risk of obesity and delayed brain development higher for boys than girls?
A new study supported by the EU-funded HELIX and ATHLETE projects has found that the risk of obesity and neurodevelopmental delay can vary for boys and girls based on certain environmental exposures during pregnancy. Published in the journal ‘BMC Medicine’, the study identifies an environment combining four exposure levels that protect girls from these conditions. For their study, the researchers analysed data from more than 1 000 children from the HELIX project. They studied the link between obesity and 93 exposures during pregnancy relating to the urban environment, chemicals, and social and lifestyle factors to see if certain exposures protected girls more than boys. They also studied clinical, neuropsychological and methylation data relating to children aged 5-11 years to assess whether these prenatal exposures are associated with epigenetic changes – DNA modifications that regulate whether genes are turned on or off. The epigenetic focus was on DNA methylation, a chemical reaction in the body in which a small molecule called a methyl group is added to DNA and which plays a critical role in normal human development.
The importance of environment
The research team classified the children into two different exposure environments called E1 and E0. E1 consisted of a combination of exposure levels that gave girls a significantly lower risk of obesity than boys, as compared to E0 that consisted of the remaining combination of exposure levels. The team also investigated whether the association between sex and neurodevelopmental delay also differed between E0 and E1. As reported in the study, E1 was defined by the combination of low dairy consumption, blood cotinine levels associated with non-smokers, and low facility richness and the presence of green spaces in the neighbourhoods where the pregnant mothers lived. The analysis of sex-environment interaction on child obesity identified E1 as a prenatal environment that offered girls significantly greater protection against obesity than boys during preteen years. “E1 was also associated with a lower risk of neurodevelopmental delay in girls, based on neuropsychological tests of non-verbal intelligence … and working memory,” write the authors. “In summary, girls in childhood may be protected against obesity if their pregnant mothers had moderate dairy consumption, non-smokers cotinine levels, and lived in environments with a low abundance of rich facilities and the presence of green spaces. The environment is also protective against the neurodevelopmental delay of non-verbal intelligence and working memory. While female protection is measured against male risk, female protection outweighs the risk of obesity in boys,” conclude the researchers in their paper. The study could help inform further efforts to raise public awareness of the impact of diet and smoking during pregnancy on obesity and neurodevelopment. The HELIX (The Human Early-Life Exposome – novel tools for integrating early-life environmental exposures and child health across Europe) project ended in 2017. ATHLETE (Advancing Tools for Human Early Lifecourse Exposome Research and Translation) ends in 2024. For more information, please see: ATHLETE project website
Keywords
HELIX, ATHLETE, pregnancy, obesity, neurodevelopment, prenatal, boy, girl, child
