Prenatal exposure to fine particles, premature rupture of membranes and gestational age: A prospective cohort study

The associations between maternal exposure to fine particles with aerodynamic diameter ≤ 2.5 μm (PM_2.5) and gestational age as well as premature rupture of membranes (PROM) remain unclear. Few studies have focused on preconception exposure and components of fine particles in China.

A total of 1715 pregnant women were enrolled at hospitals affiliated with Nanjing Medical University from 2014 to 2015. Personal exposure to PM_2.5 was estimated from preconception to the first trimester. Gestational age and PROM were investigated to explore their associations with PM_2.5 and its components.

From 12 weeks before conception to the end of the first trimester, the gestational age was reduced by 0.89 days (95% CI: -1.37, -0.40) per 10 μg/m³ increment in PM_2.5 exposure. After the exposure period was separated into two groups, PM_2.5 exposure reduced the gestational age by 0.35 days (95% CI: -0.59, -0.11) in the 12 weeks before pregnancy. With maternal exposure to PM_2.5 early in the first trimester, gestational age was reduced by 0.62 days (95% CI: -1.09, -0.14). After mediation analysis, we found that PROM mediated the association between PM_2.5 and gestational age from preconception to the first trimester. Components analysis indicated that exposure to black carbon, organic matter, and nitrate increased the risk of PROM and decreased gestational age.

Exposure to PM_2.5 as well as some components of PM_2.5 before and during early pregnancy was associated with PROM and gestational age. PROM might be a potential mediator in associations between PM_2.5 as well as various components and gestational age.