Effects of PM_2.5 exposure during gestation on maternal gut microbiota and pregnancy outcomes

A number of studies have reported that fine particulate matter (PM_2.5) exposure is associated with adverse pregnancy outcomes. Moreover, PM_2.5 exposure contributes to changes of gut microbiota. However, influences of PM_2.5 exposure during gestation on maternal gut microbiota and pregnancy outcomes were not well understood. Here we performed a study using mice models. Dams were exposed to PM_2.5 suspension by intratracheal instillation on gestational day (GD) 3, 6, 9, 12 and 15. Pregnancy outcomes, maternal gut microbiota and short chain fatty acids on GD 18 were all measured. The fetal body weight of PM_2.5 group was significantly lower than that of control group (p < 0.05). Meanwhile, the fetal body length of PM_2.5 group was significantly shorter than that of control group (p < 0.05). The Shannon or Simpson index of PM_2.5 group were higher than that of control group (p < 0.05). At the phyla level, compared to dams in control group, mice in the PM_2.5 group had higher ratio of phyla Proteobacteria, Candidatus Saccharibacteria and Fusobacteria and lower ratio of phyla Acidobacteria, Gemmatimonadetes and Deferribacteres in the gut. Compared with control group, the concentration of isobutyric acid was higher in PM_2.5 group, but butyric acid concentration was lower in PM_2.5 group (p < 0.05). These findings suggested that prenatal exposure to PM_2.5 had an effect on birth weight of fetus. Meanwhile, PM_2.5 tracheal exposure during gestation caused changes in the distribution and structure of gut microbiota of dams.