Analysis Of Short-term And Sub-chronic Effects Of Ambient Air Pollution On Preterm Birth And Estimation Of Disease Burden On Preterm Births Attributable To Maternal Fine Particulate Matter Exposure

Objective:This study aimed to evaluate the effect of short-term and sub-chronic exposure to air pollutants on preterm birth from 2014 to 2016.Also,we estimate the burdens of PTB attributable to outdoor PM2.5.Methods:1.The methods of short-term and sub-chronic effects of ambient air pollution on preterm birthGeneral additive models(GAM)were performed to examine the impact of the dailyand cumulative weekly air pollutants exposure.The non-linear patterns between adverse birth outcomes and weather condition were assessed by including penalized smoothing splines in the model.The demographic characteristics of pregnant women were also included in the model as covariates.Considering heterogeneity among different cities,we added the city as a dummy variable in adjusted model.Stratified analyses were also conducted by city.Single-pollutant and two-pollutant model were both used to analyze the associations.2.The methods of the burdens of preterm birth attributable to outdoor PM2.5We collected annual-average PM2.5 concentrations,concentration-response relationships between PM2.5 exposure during pregnancy and PTB,rates of PTB,number of live births in Hubei province in 2016.We also used Kriging model to estimate the daily concentration of PM2.5 for each area,then we evaluated annual-average PM2.5 concentrations.We converted PTB odds ratio(OR),identified in a previous prospective cohort study in Wuhan city(1.03 per 5?g/m3 for our base case,1.02-1.05 for low-and high-scenarios)to relative risk(RRs),to obtain an estimate that better represents the true relative risk.A reference levels(RL)of 15?g/m3 and 35 ?g/mlwere applied.We then used the RR estimates and county-level PTB prevalence to quantify PM2.5-attributable PTB.Then,they were combined to estimate the odds ratios(ORs),relative risks(RRs),attributable fractions(AFs),and numbers of PTB associated with PM2.5 exposure.Result:1.The results of short-term and sub-chronic effects of ambient air pollution on preterm birthA total of 16,035 cases were analyzed.Significant short-term effects of air pollution exposure at lag 1 day on preterm birth were observed.In adjusted single-pollutant city-specific model,the association between acute air pollutants exposure and preterm birth was significant in Shiyan(PM2.5:OR=1.066,95%CI 1.027-1.106;PM10:OR=1.048,95%CI:1.022-1.076;O3:OR=1.029,95%CI:1.004-1.056)and Jingzhou(PM2.5:OR=1.037,95%CI:1.008 1 1.068;PM10;OR=1.025,95%CI:1.007-1.043;SO2:OR=1.082,95%CI:1.023-1.144;NO2:OR=1.211,95%CI:1.098-1.335)per 10?g/m3 increment.Also,weekly average cumulative air pollution exposure was significantly associated with preterm birth in both areas.2.The results of the burdens of preterm birth attributable to outdoor PM2.5According to the first-class limit of PM2.5(15 ?g/m3)in the Ambient Air Quality Standards of China,an estimated 20.94%of preterm birth nationally(95%CI:13.54%-36.96%)in 2016 could be attributed to PM2.5.The AF values varied from 23.94%(95%CI:13.54%-36.96%)to 18.36%(95%CI:11.88%-32.35%).Meanwhile,according to the second-class limit of PM2.5(35 ?g/m3)in the Ambient Air Quality Standards of China,an estimated 9.59%of preterm birth nationally(95%CI:6.21%-16.89%)could be attributed to PM2.5.The AF values varied from 12.38%(95%CI:7.96%-22.08%)to 7.26%(95%CI:4.67%-12.38%).Conclusions:The results showed that there was a positive correlation between the concentration of air pollutants and the incidence of premature birth in Shiyan City and Jingzhou City from 2014 to 2016.PM2.5 With the increasing air pollution situation,exposure to high concentrations of air pollution during pregnancy caused by public health problems can not be ignored.