Researchers from the mixed unit Inserm – University of Grenoble have measured the effects of exposure to air pollutants on fetal growth and in particular the head circumference and birth weight.

The study gathered 280 pregnant women in whom fetal growth was studied at the end of each trimester of pregnancy and birth. Some participants have agreed to bear in mid-pregnancy, a device measuring the levels of benzene in ambient air, outside and inside the closed premises.

After studying the factors already known for their impact on fetal growth (body of the mother, duration of pregnancy, passive smoking), researchers were able to clearly show that exposure to air pollutants could contribute to a decrease in the weight of the child at birth. By carrying out ultrasound measurements, the scientists also found that effects on the head circumference was manifested at the end of the second trimester.

These results are valid regardless of the level of exposure to outdoor and indoor pollution. If benzene was used as a marker for this study, a mixture of hundreds of pollutants is actually responsible for these disorders. Some gases and fine particles can penetrate the lungs, to reach the air cells and thus reaching the maternal blood circulation and then fetal.

Researchers must now understand the biological mechanisms involved in this impaired fetal growth. One hypothesis is that pollution disrupt blood circulation and cardiovascular system.