Air pollution affects fetal development during pregnancy

SCIENCE – One “major risk for the smooth progress of the pregnancy”. The deleterious effects of outdoor air pollution on fetal growth are highlighted in a study by Inserm and Grenoble Alpes University published this Tuesday, May 7 in the scientific journal The Lancet Planetary Health. Researchers also note that exposure to pollution affects girls and boys differently.

For this work, the research team looked at changes in the DNA of the placenta linked to exposure to three major air pollutants in 1,500 pregnant women. The pollutants studied were fine particles PM2.5 and PM10, as well as nitrogen dioxide (NO 2). The pollution rate was measured near the homes of women, living in four French geographic regions, combining urban, peri-urban and rural areas.

Disturbed child development

Result: the scientists concluded that these pollutants caused epigenetic modifications of the placenta, that is to say that the genes change their behavior. However, they did not observe changes in the DNA sequence.

A third of these gene modifications are “directly associated with indicators of child development (birth weight and height, head circumference, duration of pregnancy, etc.)”develops the study.

Other affected genes are involved in “the development of the nervous system”. But also in the evolution “of the immune system”, with consequences – among others – the occurrence of neonatal diabetes or obesity.

Female and male fetuses are not affected in the same way

Furthermore, the effects of exposure to air pollution are not the same depending on the sex of the fetus. First, the placenta is particularly exposed in the first trimester of pregnancy for boys, and in the third trimester for girls.

Then, the alterations in fetal development are not quite the same. In boys, genes involved in the nervous system and intellect are most affected. In girls, disruption of gene activity increases the risk of “develop chronic metabolic diseases (hypertension, diabetes, obesity, etc.) later in life”underlines researchers from Inserm and Grenoble Alpes University.

“Future studies may investigate whether placental epigenetic changes caused by exposure to air pollution during pregnancy persist after delivery and how they might influence development during childhood., adds Johanna Lepeule, one of the authors of the study, in a press release. And adds that research on a global scale would make it possible to consolidate these initial results.

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