The impact of extreme air pollution on preterm birth in twin pregnancies: identifying susceptible exposure windows.

BACKGROUND

Accelerated industrialization globally has intensified air pollution, but the susceptibility periods for extreme air pollution in twin pregnancies remain undefined.

METHODS

This study investigated the association between extreme air pollution exposure and preterm birth risk in twin pregnancies. Data on 3623 twin pregnancies in Chongqing from 2017 to 2022 and air pollution readings from 12 monitoring stations were analyzed using distributed lag non-linear quasi-Poisson regression models. Additionally, four extreme air pollution indices were developed to assess the cumulative effects of lagged exposures on preterm birth risk through multivariate logistic regression.

RESULTS

Compared to the lower quartile, the 95th percentile of extreme air pollution exposure showed a positive correlation between concentrations of PM, PM, NO, SO and CO and preterm birth risk in twin pregnancies, with O inversely correlated. Sensitive periods for air pollutants were different. 8-12 and 27-35 gestational weeks were identified for PM; 6-13 and 27-35 gestational weeks were identified for PM; 5-14 and 21-33 gestational weeks were identified for NO; 4-15 and 24-36 gestational weeks were identified for SO; 4-11 and 29-33 gestational weeks were identified for CO. PM, PM, SO and O showed cumulative effects across short and long lags, while CO showed a long-term effect. Notably, NO exhibited a protective effect during all lag periods.

CONCLUSION

The study highlights gestational windows of 8-11 and 29-33 weeks as highly sensitive to extreme pollution for preterm birth in twin pregnancies, with marked risk increases during 0-3, 0-6 and 0-9-month lag periods.