Study On The Influencing Factors Of Neonatal Birth Weight And Abnormal Gestational Age Based On Generalized Additive Model

Objective:To analyze the current situation and of newborn birthweight(NBW),small for gestational age(SGA)and large for gestational age(LGA)in Fuyang,and to explore the linear and nonlinear effects of maternal and infant variables on them,so as to provide a reference for guaranteeing newborn normal birthweight.Materials and methods:The data were extracted from a three-year follow-up study in Fuyang,which focused on the married women who intended to conceive.The spearman correlation coefficient were used to find the correlation within each maternal and infant variable.In addition,the comparison of the SGA,the LGA with appropriate for gestational age(AGA)was performed.The generalized additive model(GAM)was used to fit the multivariate model of NBW,SGA,LGA,and the effect curves of each variables in the model were estimated.Results:A total of 16,741 pairs of mothers with singleton infants were included in this study,including 9512 male infants and 7229 female infants.The mean age of the mothers was 24.3 years,the mean menstrual cycle was 29.1 days,the mean gestational week was 37.9 weeks,the mean body mass index was 21.3 kg/m~2,the mean hemoglobin was 131.1 g/L,the mean blood glucose was 4.8 ml/L,the mean gestational times and births were 1.6 times and 1.5 times respectively.The maximum NBW was 8.0 kg,the minimum was 0.8 kg,and the average was 3.5 kg.A total of 581cases were found to be SGA,accounting for 3.47%,and 5317 cases were found to be LGA,accounting for 31.76%.The results of the multivariate GAM model were shown as follows.In the whole interval of gestational age,NBW showed an upward trend in the interval[28,42]weeks,and a downward trend in the interval[42,44]weeks.Female babies weighed 0.101 kg less than male babies(?=-0.101,P<0.001).The babies with mothers taking iron and folic acid(IFA)earlier weighed 0.019 kg more than those mothers with free taking(?=0.019,P<0.001).There was a nonlinear effect between menstrual cycle,gestational age and creatinine level and SGA.SGA and gestational age were positively correlated within the interval of gestational age[28,33]weeks,negatively correlated within the interval of[33,42]weeks,and positively correlated within the interval of[42,44]weeks.In the interval of creatinine level[17,76]micromol/l,the risk of SGA decreased with the increase of creatinine level,while in the interval of[76,148]umol/L,the risk of SGA increased with the increase of creatinine level.In the interval of[20,28]days,[34,41]days,the risk of SGA increased with the increase of the number of days of the menstrual cycle,while in the interval of[28,34]days,[41,60]days,the risk of SGA decreased with the decrease of the menstrual cycle.Gestational age,creatinine level had a nonlinear effect with LGA,which was positively correlated with gestational age in the interval of[28,33]weeks,negatively correlated in the interval of[33,40]weeks,and positively correlated in the interval of[40,44]weeks.Within the whole interval of creatinine level[17,148]umol/L,the risk of LGA decreased with the increase of creatinine level.Body mass index(OR=1.02,95%CI:1.00-1.03),blood sugar(OR=1.05,95%CI:1.01-1.11),gravidity(OR=1.20,95%CI:1.11-1.31),female neonates(OR=0.64,95%CI:0.59-0.69),IFA dummy variable 2(early intake vs.no intake)(OR=1.22,95%CI:1.05-1.39),IFA dummy variable 3(late intake vs.no intake)(OR=1.19,95%CI:1.05-1.32),IFA dummy variable 4(persistent intake vs.no intake)(OR=1.67,95%CI:1.34-2.09)increased the risk of LGA.It was also found that there was an interaction of gestational age with gravidity and creatinine level.Conclusion:Based on the GAM model,this study found that the linear and nonlinear effects of NBW,SGA and LGA and related maternal and infant variables were different in the effect variation curves of each variable and interval.Among them,gestational age and NBW were nonlinear effects.There were nonlinear effects on menstrual cycle,gestational age,creatinine level and SGA.Nonlinear effects were also found between gestational age,creatinine level and LGA.Taking folic acid could increase NBW,but should be aware that it increases the risk of LGA.The female fetus were negatively linked with the risk of LGA,and the body mass index,blood glucose,and parity were positively and linearly correlated with the risk of LGA.