Association Between The Body Composition During Early Pregnancy And Macrosomia Risk Determined Using Propensity Score Matching

BackgroundOverweight or obesity before pregnancy and excessive weight gain during pregnancy are becoming increasingly prevalent worldwide,and are associated with pregnancy complications and adverse pregnancy outcomes including gestational hypertension,gestational diabetes and macrosomia.Macrosomia is the most common adverse outcome of pregnancy,and is associated with several maternal and fetal complications such as maternal birth canal trauma,shoulder dystocia,perinatal asphyxia and even death.In the long term,newborns with macrosomia are more likely than newborns with a normal birth weight to be obese in childhood,and these individuals also have an increased risk of metabolic complications such as obesity and diabetes in adulthood.Previous studies suggested that macrosomia is associated with and induced by diverse factors,including both genetic and environmental factors,as well as gestational diabetes.Several reports have shown that factors like a high pre-gestational body mass index(BMI)and excessive weight gain during pregnancy are independent risk factors for macrosomia.The body composition may be evaluated to assess a patient's nutritional status,and generally includes the body fat(FM),muscle mass(MM),fat-free mass(FFM)among other parameters.Bioelectrical impedance analysis(BIA),computed tomography(CT),magnetic resonance imaging(MRI),and dual-energy X-ray absorptiometry(DEXA)are common technologies used to determine the body composition.Due to safety concerns,only BIA is applied during pregnancy.However,BIA can determine various indices including the fat mass,fat mass percentage,fat-free weight,intracellular water and extracellular water.There have been several investigations about the association between the body composition during pregnancy,especially the fat mass,and the incidence of macrosomia,however,most of these were observational or non-randomized studies which might have had selection bias.The purpose of this study was to investigate the association between the body composition during early pregnancy and the incidence of macrosomia using propensity score matching to control for potential confounding bias.It is anticipated that this study will provide clinical evidence to support routine body composition testing during early pregnancy.MethodsThis study uses a case-control designThe study population was pregnant women who delivered a single fetus at Yongchuan Maternity and Child Hospital of Chongqing between November 2016 to July 2017 The case-control status was determined based on the body weight of the newborn.The pregnant women whose newborns weighed ?4000g were assigned to the macrosomia case group,while the pregnant women whose newborns weighed <4000 g were assigned to the control group.The delivery information,body composition in the early trimester(5-13 weeks of gestation)and general information of the two groups were recorded.The propensity score matching was performed based on the maternal age,gestational week,the week the body composition was measured,gestational weight gain,and the sex of the newborn.The case group and the matched control group formed the matched sample.The STATA 12.0 software was used for matching.We compared the differences in body composition between the case and control groups after matching.In addition,we explored the association between the body composition during early pregnancy and the risk of macrosomia.SPSS 25.0 was used for the statistical analysis.ResultsThere were a total of 1721 pregnant women who delivered a single fetus in the hospital.Based on the inclusion and exclusion criteria,a total of 1522 mother/neonate pairs were included.The mean maternal age was 28.09 ±4.83 years old,the mean number of pregnancies was 2.60±1.45,the incidence of pregestational diabetes mellitus was 1.3%,and the incidence of gestational diabetes mellitus was 26.4%.There were 88 cases(5.8%)of macrosomia in this group.Matching was performed according to maternal age,gestational week,the week the body composition was measured,the gestational weight gain,and the sex of the newborn.There were 264 cases matched successfully,including 88 cases of macrosomia and 176 newborns with a normal birth weight.After matching,there were no statistically significant differences in the maternal age,gestational week,the week the body composition was measured,gestational weight gain,or the sex of the newborn between the two groups.When the BMI and body composition during early pregnancy were compared between groups,the pre-pregnancy BMI,current BMI,total body water,intracellular water,extracellular water,and a fat mass percentage ?30% during early pregnancy were higher in the macrosomia group than in the normal birth weight group.The fat-free mass of the case group was lower than that in the control group.A univariate logistic analysis showed that a high pre-pregnancy BMI,prior delivery of an infant with macrosomia,and a higher total body water,intracellular fluid,extracellular fluid and fat mass percentage were risk factors for macrosomia,while a higher fat-free mass percentage was a protective factor against macrosomia.Gestational diabetes mellitus and pregestational diabetes mellitus were not significantly correlated with macrosomia.To isolate the potential confounding effects,a multivariate logistic regression model was used to analyze the correlation between the body composition in early pregnancy and the risk of macrosomia after adjusting for the times of pregnancy,parity,gestational diabetes mellitus and pregestational diabetes mellitus.The results suggested that the pre-pregnancy BMI,and the BMI and fat mass percentage during early pregnancy were independent risk factors for macrosomia,while the fat-free mass percentage was an independent protective factor.Pregnant women with a history of delivering an infant with macrosomia had a 6.47-fold higher risk of delivering a second infant with macrosomia than those without this history.Women in early pregnancy with a fat mass percentage ?30% had a 1.86-fold greater risk of having an infant with macrosomia than those with a fat mass < 30%.ConclusionsThe pre-pregnancy BMI,the BMI in early pregnancy,and the fat mass percentage during early pregnancy were independent risk factors for macrosomia,while the fat-free mass percentage was an independent protective factor.These findings might provide clinical evidence to support body composition testing during early pregnancy.Nutritional consulting,intervention and standardized body weight management for women with a history of macrosomia,a higher BMI in early pregnancy and a fat mass percentage ? 30% might help to decrease the risk of macrosomia.