The Acute Effect Of Air Pollution On Premature Rupture Of Membranes In Hefei:A Time Series Study

BackgroundIn recent years,various studies have already investigated the effect of air pollution on people’s health,especially for the developing fetus and pregnant women and mainly focus on preterm delivery,low birth weight,small for gestational age.However,there is little evidence on the association between air pollutants and premature rupture of membranes（PROM）.ObjectivesThe main objective of the present research is to analyze the general characteristics and the association between PROM and air pollutant levels in Hefei urban area from January 1,2016 to December 31,2018.A subgroup analysis was conducted to further investigate the effects of season and age on the modification of air pollution-induced PROM,aiming to provide epidemiological basis for controlling air pollution and protecting vulnerable population.MethodDaily PROM data,including maternal age,number of fetuses,residence and other information of pregnant women in Hefei were collected from January 1,2016 to December 31,2018,while the daily air pollutants and meteorological factor data were collected during the same period.In this study,we performed a time series study to evaluate the association between PROM and air pollution after controlling the confounding factors such as the long-term trend of time,day of the week effect,seasonal trend and meteorological conditions by using the"mgcv"package of R software.ResultsIn the present study,there are a total of 6,899 PROM mother-child pairs women with PROM,of which 80.3%were younger than 35 years old.The distribution of air pollutants is seasonally and periodically,and the daily average concentrations of PM_2.5,PM₁₀,SO₂,NO₂ and CO were 54.58μg/m³,77.72μg/m³,13.06μg/m³,46.09μg/m³ and0.90mg/m³,respectively,while the daily maximum 8-hour average of O₃ concentration was 95.67μg/m³.The time series study found that exposure to gaseous pollutants can significantly increase the risk of PROM.The effects of SO₂,NO₂,and O₃ reach their maximum effects at lags of 4,06,and 09 days,respectively.For every 10μg/m³increase in concentration,the risk of PROM increases by 8.74.%（95%CI:2.12%～15.79%）,3.09%（95%CI:0.64%～5.59%）and 1.68%（95%CI:0.28%～3.09%）.But no significant association between PM_2.5 and PROM was found.Seasonal stratification analysis showed that the effects of PM_2.5,SO₂ and O₃ on PROM were more significant in the cold season,and only the effect of NO₂ on PROM was observed in the warm season.When age was included in the stratified analysis,the effects of SO₂ and NO₂exposure on PROM were higher in the younger mothers（<35 years old）compared to the advanced mothers（≥35 years old）,while the older group was more vulnerable to O₃ damage than the younger group.The results of the dual pollutant model show that NO₂ exposure has independent harmful effects,while SO₂ and O₃ may not have independent harmful effects.ConclusionFrom 2016 to 2018,the air pollutant levels in Hefei showed seasonal and cyclical trends,and the level of PM_2.5,PM₁₀,SO₂,NO₂,and CO were high in winter,while the concentration of O₃was high in summer.There is a great positive correlation between PROM and the increased gaseous pollutants,and the association is stronger in cold season.Moreover,the effects of SO₂ and NO₂ exposure on the younger group and O₃exposure on the older group were more significant.