| Background:Although studies have assessed the associations between prenatal exposure with fine particulate matter(PM2.5)with birth weight,few have identified the susceptible exposure window and investigated the associations of PM1.Additionally,a baby boom occurred after China implemented the universal two-child policy,but whether the associations between prenatal fine particulate matter exposure and birth weigh are modified by second-born and advanced maternal age remains unknown.Objectives:The objective of this study was to estimate the associations between prenatal exposure to PM(PM2.5 and PM1)and birth weight,identify the susceptible exposure windows,and assess the modifying effects of birth order on the PM exposure.All participants were slected from the Prenatal Environment and Offspring Health（PEOH）birth cohort condcuted since 2016 in Guangzhou,China.Methods:A spatiotemporal land-use-regression（ST-LUR）model was used to estimate a pregnant woman’s weekly PM2.5 exposure,and a generalized additive model（GAM）was used to estimate each PM1 exposure.A distributed lag non-linear model（DLNM）was applied to assess the exposure-lag-response associations between weekly PM exposure and birth weight.Results:The sample included 4,086 pairs of pregnant women and newborns.The results showed that maternal exposure to PM2.5 and PM1 during the 15th to 24th and 16th to 24th gestational weeks were associated with lower birth weight,the strongest association was observed in the 19th week,during which each 10μg/m3 increment in PM2.5 and PM1 was associated with a 1.47g（95%CI:0.44g,2.49g）and 1.58g（95%CI:0.41g,2.74g）decrease in birth weight,respectively.Compared with the first-born neonates,greater associations of PM2.5 and PM1 exposure on birth weight were observed among the second-born neonates in the 15th to 21st and 15h to 22nd gestational weeks,and the strongest associations were observed in the 18th gestational week.Each 10 μg/m3 increase in the exposure to PM2.5 and PM1 during the 18th gestational week was associated with 2.12 g（95%CI:0.51g,3.72g）and 2.39g（95%CI:0.56g,4.22g）decrease in birth weight.In addition,compared with non-advanced-age pregnant women’s neonates,greater associations of PM2.5 and PM1 exposure on birth weight were both observed among the advanced-age pregnant women’s neonates in the 12th to 30th gestational weeks,and the strongest associations were observed in the 22nd and 21st gestational week,respectively.Each 10 μg/m3 increase in the exposure to PM2.5 and PM1 during the 22nd and 21st gestational week was associated with 5.75g（95%CI:3.46g,8.04g）and 6.37g（95%CI:3.83g,8.92g）decrease in birth weight.Conclusion:This study found that higher prenatal exposure to PM2.5 and PM1 were associated with a decrease in birth weight,and PM1 may have stronger associations than PM2.5.The 15th to 24th and 16th to 24th gestational weeks might be the susceptible exposure window for PM2.5 and PM1.The associations between prenatal PM2.5 and PMi exposure and birth weight may be modified by the second-child and advanced maternal age,and greater associations of PM2.5 and PM1 were found in second-born neonates and advanced-age pregnant women’s neonates.Therefore,pregnant women should take measures such as improving indoor air quality or decreasing activity time outdoors to reduce personal fine PM exposure during pregnancy,especially in the potentially relevant exposure window.In addition,further studies tracking the health of the secondborn children are warranted because they may be more sensitive to environmental factors than the first-born children. |
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