| Objectives:(1)To investigate the effect of prenatal exposure to particulate matter(PM)on newborn growth and the sensitive window,and to explore the dose-response relationship between maternal PM exposure level with newborn development.(2)To investigate the effect of prenatal exposure to PM on infant growth within 24months and the sensitive window,and to explore the dose-response relationship between maternal PM exposure level with infant growth.Methods:All participants were from Tongji Maternal and Child Health Cohort(TMCHC),who were enrolled from January 2013 to December 2016.The basic information of pregnant women was obtained through a questionnaire survey when they attended the first prenatal visits.Based on the home address of pregnant women,using information including satellite remote sensing aerosol optical depth,ground PM real-time monitoring data,land use information,meteorological data,and other spatiotemporal factors,we used the random forest model to estimate the monthly,trimester-specific,and whole pregnancy average exposure levels of submicron particulate matter(PM1.0),fine particulate matter(PM2.5)and inhalable particulate matter(PM10).(1)Newborn growth information,including birth weight(BW)and birth length(BL),were obtained from electronic medical records of maternity delivery hospitals,and then the ponderal index(PI)was calculated.Linear regression models were used to assess the relationship between neonatal BW,BL,and PI with PM exposure levels in the first,second,third,and whole trimester of pregnancy.Distributed lag model(DLM)was used to assess the effects of monthly exposure level of PM on newborn growth.The restricted cubic spline(RCS)function was used to explore the dose-response relationship between maternal PM exposure level during the entire pregnancy and neonatal development.The corresponding cut-points were identified by piecewise linear regression and recursive experimental method.(2)At 3,6,12,and 24 months postpartum,telephone follow-up was conducted for the subjects to obtain the infants'weight,length,and other information,then the body mass index(BMI)was calculated.According to the infant growth standards proposed by the World Health Organization,weight,length,and BMI were converted into z-scores,namely,weight-for-age z score(WAZ),length-for-age z score(LAZ),and BMI-for-age z score(BAZ).Linear regression was used to analyze the relationship between PM exposure level during the entire pregnancy with the WAZ,LAZ,BAZ,and logistic regression was used to analyze the relationship between PM exposure level during the whole pregnancy with the risk of overweight(BAZ>2)and rapid weight gain(?WAZ>0.67)of infants.The generalized estimated equation(GEE)was used to analyze the relationship between trimester-specific PM exposure level and outcomes.DLM was used to analyze the effect of monthly PM exposure during pregnancy on infant growth.RCS was used to explore the dose-response relationship between maternal PM exposure level during the entire pregnancy and infant growth.The corresponding cut-points were identified by piecewise linear regression and recursive experimental method.Results:(1)A total of 7655 subjects were included in analyzing the association between PM exposure level during pregnancy and newborn growth.The average age of the pregnant women was 28.2±3.5 years old,the average BW was 3328±440 g,the BL was 50.0±1.5 cm,and the PI was 26.5±2.9 kg/m3.The average PM1.0 exposure levels of pregnant women in the first,second,and third trimesters were 55.42?g/m3,51.17?g/m3,and48.62?g/m3,respectively.PM2.5 exposure levels were 67.07?g/m3,62.11?g/m3 and59.02?g/m3,respectively.PM10 exposure levels were 103.93?g/m3,98.52?g/m3 and94.94?g/m3,respectively.For the whole pregnancy,the exposure levels were:PM1.0:51.72?g/m3,PM2.5:62.71?g/m3,PM10:99.10?g/m3.Results from multiple linear regression models indicated that,after adjusting for the mother's age,education,income,pre-pregnancy BMI,season of pregnancy,year of pregnancy,gestational weight gain,smoking,drinking,exercise,pregnancy complications,gestational age,delivery mode,parity,and infant gender,the changes of newborn BW(g)were PM1.0:-8.79(95%CI:20.22,2.64),PM2.5:-11.01(95%CI:-20.49,-1.53),and PM10:-9.05(95%CI:-16.49,-1.60)with 10?g/m3increment in PM exposure level during the first trimester.The effects of PM exposure in the second trimester(per 10?g/m3)on newborn BW(g)were PM1.0:-12.70(95%CI:-24.60,-0.80),PM2.5:-12.14(95%CI:-21.91,-2.38),and PM10:-8.57(95%CI:-16.22,-0.91).The effects of PM exposure in the third trimester(per 10?g/m3)on newborn BW(g)were PM1.0:4.15(95%CI:-7.68,15.98),PM2.5:1.76(95%CI:-8.01,11.54),and PM10:1.25(95%CI:-6.36,8.87).With 10?g/m3increment in PM exposure level during the entire pregnancy,the changes of neonatal BW(g)were PM1.0:-23.21(95%CI:-45.92,-0.50),PM2.5:-26.01(95%CI:-44.20,-7.82),and PM10:-12.52(95%CI:-24.00,-1.03).The effects of trimester-specific PM exposure on neonatal PI were similar to that on BW.The DLM analyses showed that PM1.0,PM2.5,and PM10 exposure levels during the 3-6 months of gestation were related to the decrease of neonatal BW and PI.RCS analyses showed that there was a threshold effect of PM exposure throughout pregnancy on neonatal BW and PI.The association between PM exposure level and neonatal BW was not statistically significant until PM concentration reached the cut-points.When PM concentration exceeded the cut-points,BW and PI of the newborn declined sharply with the increase of PM exposure level.The cut-points of threshold effect recognized by piecewise linear regression and recursive experiment were PM1.0:57.78?g/m3,PM2.5:69.79?g/m3,and PM10:108.01-108.18?g/m3.(2)A total of 5007 subjects were included in analyzing the association between PM exposure level during pregnancy and infant growth.WAZ of infants at 3 months,6months,12 months and 24 months of age were 0.97±0.93,0.98±0.97,0.75±0.90 and0.60±0.94,respectively;LAZ were 0.91±1.09,0.95±1.09,0.72±1.08 and 0.57±1.03,respectively;and BAZ were 0.63±1.06,0.59±1.09,0.47±1.05 and 0.40±1.09,respectively.The proportions of overweight at 3,6,12 and 24 months of age were 9.5%,9.2%,7.3%and 6.0%,respectively,and of rapid weight gain were 59.0%,58.1%,49.2%and 43.7%,respectively.Multiple linear regression analyses found that after adjusting for age,education,pregnancy BMI,the season of pregnancy,year of pregnancy,parity,gestational weight gain,smoking,gestational age,infant gender,BW(except for LAZ models),BL(in LAZ,BAZ,and overweight models only),age of adding supplementary food(only after 12 months of age),with 10?g/m3increment in PM1.0,PM2.5 and PM10exposure level during the entire pregnancy,WAZ increased by 0.09(95%CI:0.02,0.16),0.08(95%CI:0.02,0.13)and 0.05(95%CI:0.01,0.08)at 12 months,respectively.And the association was only significant in boys after stratified by infant gender.Logistic regression analyses results showed that the risk of rapid weight gain at 6 months increased by 23%(OR:1.23;95%CI:1.01 1.50)and 12%(OR:1.12;95%CI:1.02,1.24)for each 10?g/m3 increase in PM1.0 and PM10 exposure level in the entire pregnancy,respectively.Results from GEE and DLM analyses were consistent that PM exposure level in the third trimester(7-9 months of gestation)was associated with increased WAZ,BAZ,and risk of overweight and rapid weight gain of infants at 12 and 24 months of age.RCS analyses showed a threshold effect of PM exposure during the entire pregnancy on infant WAZ and BAZ at 24 months of age.The associations between PM exposure level and infant WAZ and BAZ at 24 months were not statistically significant until PM concentration reached the cut-points.When PM concentration exceeded the cut-points,infant WAZ and BAZ at 24 months increased sharply with the increase of PM exposure level.The cut-points of threshold effect recognized by piecewise linear regression and recursive experiment were PM1.0:59.59-59.94?g/m3,PM2.5:72.38-72.52?g/m3,and PM10:111.77?g/m3.Conclusions:(1)The increase of maternal exposure levels of PM1.0,PM2.5,and PM10 during the first trimester,the second trimester,and the entire pregnancy were associated with decreased neonatal BW and PI.The 3-6 months of gestation was the sensitive window for PM exposure affecting newborn growth.There were threshold effects of maternal PM exposure during the entire pregnancy on neonatal BW and PI.(2)The increase of maternal exposure level of PM1.0,PM2.5,and PM10 in the entire pregnancy was associated with increased risk of rapid weight gain at 6 months of age and increased WAZ at 12 months of age;the associations were more significant in boys.The third trimester(7-9 months of gestation)was a sensitive window for PM exposure to accelerate infant development at 12 and 24 months of age and increase the risk of overweight and rapid weight gain.There was a threshold effect of maternal PM exposure during the entire pregnancy on infants'WAZ and BAZ at 24 months of age. |
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