Impact of short-term air pollution exposure on premature rupture of membranes in the North China Plain, 2015-2021: a multicity case-crossover study.

BACKGROUND

The effects of short-term air pollution exposure on hospital admissions for premature rupture of membranes (PROM) were still controversial.

METHODS

Daily data on PROM hospitalisations and air pollutants were collected from 1 January 2015 to 31 December 2021, across five cities in the North China Plain. We investigated the associations between short-term (lag0-7) exposure to air pollutants, including fine particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3), as well as composite air pollution indicators, including air quality index (AQI) and air quality composite index (AQCI). We further assessed the modifying effects of age (<35 and ≥35 years), season (cold and warm seasons), and the 'Three-Year Action Plan' (before and after implementation) on the above associations.

RESULTS

A total of 16 503 mothers with PROM were included. For each interquartile range (IQR) increase, the strongest relative risks (RRs) were 1.024 (95% confidence interval (CI) = 1.001-1.047, P < 0.05) in PM2.5 in lag3 (IQR = 48 μg/m3), RR = 1.036 (95% CI = 1.009-1.063, P < 0.05) in CO in lag4 (IQR = 0.49 mg/m3), RR = 1.024 (95% CI = 1.003-1.044, P < 0.05) in AQI in lag3 (IQR = 53), and RR = 1.026 (95% CI = 1.001-1.050, P < 0.05) in AQCI in lag3 (IQR = 2.9). The effects of exposure to PM2.5, NO2, SO2, CO, AQI, and AQCI on PROM were stronger in mothers aged <35 years, and the effects of exposure to PM10, NO2, and SO2 on PROM were stronger during the warm season (all P modification<0.05).

CONCLUSIONS

Short-term air pollution exposure was related to elevated hospital risk of PROM. The effects were more pronounced among mothers aged <35 years and during the warm season.