Maternal exposure to ambient fine particulate matter and risk of premature rupture of membranes in Wuhan, Central China: a cohort study

BACKGROUND: The associations between maternal exposure to ambient PM(2.5) during pregnancy and the risk of premature rupture of membranes (PROM) and preterm premature rupture of membranes (PPROM) are controversial. And no relevant study has been conducted in Asia. This study aimed to determine the association between maternal exposure to ambient PM(2.5) during pregnancy and the risk of (P)PROM. METHODS: A cohort study including all singleton births in a hospital located in Central China from January 2015 through December 2017 was conducted. Multivariable logistic regression models, stratified analysis, generalized additive model, and two-piece-wise linear regression were conducted to evaluate how exposure to ambient PM(2.5) during pregnancy is associated with the risks of PROM and PPROM. RESULTS: A total of 4364 participants were included in the final analysis, where 11.71 and 2.34% of births were complicated by PROM and PPROM, respectively. The level of PM(2.5) exhibited a degree of seasonal variation, and its median concentrations were 63.7, 59.3, 55.8, and 61.8 μg/m(3) for the first trimester, second trimester, third trimester, and the whole duration of pregnancy, respectively. After adjustment for potential confounders, PROM was positively associated with PM(2.5) exposure (per 10 μg/m(3)) [Odds Ratio (OR) = 1.14, 95% Confidence Interval (CI), 1.02–1.26 for the first trimester; OR = 1.09, 95% CI, 1.00–1.18 for the second trimester; OR = 1.13, 95% CI, 1.03–1.24 for the third trimester; OR = 1.35, 95% CI, 1.12–1.63 for the whole pregnancy]. PPROM had positive relationship with PM(2.5) exposure (per 10 μg/m(3)) (OR = 1.17, 95% CI, 0.94–1.45 for first trimester; OR = 1.11, 95% CI, 0.92–1.33 for second trimester; OR = 1.19, 95% CI, 0.99–1.44 for third trimester; OR = 1.53, 95% CI, 1.03–2.27 for the whole pregnancy) Positive trends between the acute exposure window (mean concentration of PM(2.5) in the last week and day of pregnancy) and risks of PROM and PPROM were also observed. CONCLUSIONS: Exposure to ambient PM(2.5) during pregnancy was associated with the risk of PROM and PPROM.