Association Between Pre-pregnancy BMI,Children BMI Trajectory And High Blood Pressure In Preschool Children: A Population-based Birth Cohort Study

ObjectivesTo get knowledge of the blood pressure(BP)level and the detection of high blood pressure(HBP)in preschool children in Ma’anshan area,and explore the association between pre-pregnancy BMI,weight gain during pregnancy and HBP in preschool children.To investigate the BMI development trajectory of children aged 0-48 months,and explore the influence of different BMI trajectories on children’s HBP detection.Futhermore to confirm whether there is an interaction effect between the pre-pregnancy BMI and BMI trajectory of children in the association with children’s HBP.Provide scientific evidence for Hypertension primary prevention and weight management of children during early childhood.MethodsOur study population from the Ma’anshan Birth Cohort(MABC),briefly 3,240pregnant women who had visited in Ma’anshan Maternal and Child Health-Care Hospital between May 2013 and September 2014 were enrolled in this cohort.We visited them in first,second,third trimester until delivery,then continued follow-up their offspring to preschool period.Excluding 1,028 mother-child pairs which non-singleton live births,missing pregnancy weight gain information,missing birth weight information,having birth defects,missing physical measurements and BP measurements at 4 years old,we finally included 2,266 mother-child pairs into our analysis.The uniformly trained investigators collected pregnants information about sociodemographic characteristics,weight before pregnancy,pregnancy history,smoking and drinking during pregnancy by the Maternal and Child Health Registration.Obtained pregnancy complications diagnosisand information and children birthoutcome information from medical record.The obstetrician measured the height and weight of the pregnant woman in every visit.We followed up the children respectively at 42 days,3,6,12,18,24,30,36,42,and 48months after birth.Our researchers measured length(height),weight,and BP(only 42 or48 months)for children in every visit,meanwhile collect feeding information through questionnaires.According to BP reference by age and height for Chinese children aged3-17 years,we defined HBP as systolic BP and/or diastolic BP≥95th percentile BP cutoff.We use group-based trajectory models(GBTM)to fit the BMI trajectory of children aged0-48 months.Mutiple logistic regression models were used to investigate the association between children’s HBP and pre-pregnancy BMI,maternal weight gain,children’s BMI trajectory.ResultsIn our study,the overall HBP detection rate was 15.7%(boys 16.5%,girls 14.9%).After adjusted confounding factors which included maternal age,gestational hypertension,gestational diabetes,maternal smoking,drinking,birth weight,small for gestational age,premature delivery,feeding patterns in 6 months,we observed there is a significant correlation between pre-pregnancy BMI and children’s HBP.Compared with normal weight defore pregnance,those pregnant women with low weight before pregnancy(BMI<18.5 kg/m~2),their offspring have lower HBP detection in preschool period(OR=0.61;95%CI:0.44-0.85).Sex stratification analysis demonstrated that the association was stronger in girls.Additionly,our study did not find siginificant association between weight gain during pregnancy and children’s HBP(P>0.05).The BMI development patterns at the age of 0 to 48 months can be divided into 4trajectory types:low level,medium level,high level,and over high level.Univariate analysis showed that weight gain during pregnancy,gestational hypertension,gestational diabetes,pre-pregnancy BMI,birth weight,and feeding pattern in 6 month,HBP in preschool period may have association with BMI trajectories.Mutiple logistic regression analysis showed that there are positive association between over high BMI trajectories and HBP,(OR=2.00;95%CI:1.16-3.44).We found there is interaction betweeen pre-pregnancy BMI and children’s BMI trajectories when associated with children’s HBP.Stratification analysis demonstrated that when maternal pre-pregnancy BMI was low weight there are no significant association between children’s high BMI trajectories and HBP.The sensitivity analyses also showed that lower pre-pregnancy BMI and higher BMI trajectories in early childhood were significant associated with HBP in preschooler.ConclusionsThe detection rate of HBP in preschool children at a relatively high level in Ma anshan area.For pregnant keeping low BMI before pregnancy has a certain protective effect of offspring HBP during preschool period.The children aged 0-48 months BMI development trajectory can be divide into four different types.Over high BMI trajectory is associated with increased detection rate of HBP,and maternal low BMI before pregnancy may be change this adverse effect.