Prenatal exposure to gaseous air pollution in relation to worse fetal growth and adverse birth outcomes in mice

Prior studies have linked prenatal exposure to air pollutants with adverse pregnancy outcomes, but few have empirically and experimentally investigated the causal effects on adverse outcomes, abortion, and fetal abnormalities. The aim of this study was to estimate the combined effects of prenatal exposure to gaseous air pollutants (CO, SO2, and NO2) on fetal growth markers (i.e., placental weight (PW), placental diameter (PD), fetal weight (FW), and crown-to-rump length (CRL)) and fetal abnormalities. We used NMRI mice during three pregnancy periods (gestational days (GD) 1: 0.5-5.5 days, GD2: 6.5-14.5 days, GD3: 14.5-17.5 days) that matched milestones in human development stages. The mice were categorized into control and experimental groups. All groups had the same baseline conditions in terms of age and weight. The experimental groups were placed in a chamber containing air pollutants every day for 1 h during 3 pregnancy periods. Exposure to air pollution during different periods of pregnancy showed a significant association with adverse pregnancy outcomes. Fetal growth markers in experimental groups were adversely affected by stress conditions caused by air pollutants, showing significant declines in FW and CLR (P < 0.001 during GD 6.5-14.5 and GD 14.5-17.5) and PW and PD (P < 0.001) during GD 6.5-14.5. Preterm births and abortion were only observed in the exposure group, and we found significant associations between exposure to air pollution and abortion and fetal abnormalities in the second and third periods of pregnancy. In addition, we found that the highest risk of adverse outcomes on fetal growth markers is on the dangerous threshold of exposure to pollutants, and the highest frequency of fetal abnormalities included central nervous system defects, hemangioma, and organ defects. Our findings suggest that maternal exposure to gaseous air pollution during pregnancy is adversely affecting fetal growth markers and pregnancy outcomes in mice.

Automated summary

This study found that prenatal exposure to gaseous air pollutants adversely affects fetal growth markers and pregnancy outcomes in mice. The exposure to air pollution during different periods of pregnancy showed a significant association with adverse pregnancy outcomes, including preterm births, abortion, and fetal abnormalities.