A study published within the journal BMC Medicine describes that the danger of obesity and neurodevelopmental delay can vary between girls and boys concerning certain kinds of prenatal exposures. The study identifies a mix of 4 exposure levels that protect girls from developing these complications. 

Study: Prenatal environmental exposures related to sex differences in childhood obesity and neurodevelopment. Image Credit: Chanintorn.v / Shutterstock

Background

Developmental variation between girls and boys has been observed in lots of biological processes, including susceptibility to infection, neurological development, and pathogenesis of common diseases, especially obesity. There’s evidence showing a better prevalence of obesity in boys than girls in 96% of high-income countries the world over.

Despite significant variation in development between girls and boys, studies mainly consider sex as a confounding factor and never a causative factor. Studies investigating the results of environmental aspects on biological processes (exposome studies) primarily aim to research large-scale data collected on the individual- or population level in order that probably the most appropriate interventions might be identified and timely applied to the appropriate population. Since sex is the most important difference between individuals, it’s a prerequisite for exposome studies to analyze how environmental aspects affect sexual variations in development and disease.   

In the present study, scientists have developed a way of casual modeling to find out the profiles of certain prenatal exposures that will protect girls greater than boys against obesity and neurodevelopmental delay.

Moreover, the scientists have evaluated whether these prenatal exposures are related to epigenetic changes, especially DNA methylation patterns, in girls and boys during their preteen years. 

Study design

The scientists analyzed the info of 1044 children collected from the Human Early Life Exposome (HELIX) study conducted in Europe. Specifically, they analyzed clinical, neuropsychological, and methylation data during childhood (5 – 11 years) that were related to 93 prenatal exposures.

They conducted an exposome-wide interaction evaluation to discover prenatal exposures with the best impact on the sexual variation in obesity risk and neurodevelopmental delay. They classified the youngsters into two different environments, namely E1 and E0.

The E1 environment included a mix of exposure levels where girls have a significantly lower risk of obesity than boys, as in comparison with the E0 environment, which included the remaining combination of exposure levels. Additionally they investigated whether the connection between sex and neurodevelopmental delay differs between E1 and E0.

Vital observations

The evaluation of obesity risk and neuropsychological measures within the study population revealed a lower frequency of obesity amongst girls in comparison with that amongst boys. Furthermore, girls showed a significantly lower risk of attention deficit hyperactive disorder (ADHD) than boys.

The exposome-wide evaluation of sex-prenatal exposure interactions on obesity revealed that dairy consumption and blood cotinine levels while pregnant are major risk aspects for ladies. For boys, facility richness and green spaces while pregnant were identified as potential protective and risk aspects.

The scientists further analyzed whether a mix of those exposures creates specific environments where one sex is more prone to developing obesity than the opposite sex. 4 identified prenatal exposures were used to develop a multi-exposure profile, which was further used to categorise the whole study population.

About 64% of the youngsters were classified into the E1 environment, which was characterised by moderate dairy consumption, non-smokers’ cotinine levels, low abundance of wealthy facilities, and the presence of green spaces. The remaining of the youngsters were classified into the E0 environment consisting of the remaining combos of exposure levels.   

The evaluation of sex-environment interaction on obesity risk identified E1 as a prenatal environment where girls are significantly more protected against obesity than boys during preteen years.

Further evaluation of sexual variation in neurodevelopment based on neuropsychological tests of non-verbal intelligence and dealing memory revealed that E1 can also be related to a lower risk of neurodevelopmental delay in girls than in boys. 

Epigenome-wide association study between the environments was conducted using DNA methylation data. The evaluation identified several biological processes, especially synapse reorganization and structural and functional regulation of synapses, that are directly related to neurodevelopment.

Study significance

The study reveals that girls born to moms with moderate dairy consumption, non-smokers’ cotinine levels within the blood, low abundance of wealthy facilities, and green space exposure while pregnant have a significantly lower risk of developing childhood obesity and neurodevelopmental delay than boys.