Pre-pregnancy Body Mass Index And Gestational Weight Gain With The Maternal-fetal Outcomes Of Twin Pregnancies

Objective By studying the relationship between the Prep-pregnacy body mass index、gestational weight gain（GWG）and the maternal-fetal outcomes,we explored the appropriate range of gestational weight gain in twin pregnancies,which supposed to provide evidence for the weight management of twin pregnancies before pregnancy and during pregnancy.Methods A total of 1056 twin pregnancy who gave birth at the Third Affiliated Hospital of Zhengzhou University from January 1,2016 to June 30,2018 were selected.Their age,height,Pre-pregnancy weight,gestational age,pre-delivery weight,pregnancy complications（such as hypertensive disorder complicating pregnancy,gestational diabetes,pregnancy with hypothyroidism,pregnancy with anemia,etc.）.delivery methods,postpartum hemorrhage,neonatal birth weight and birth status are extracted and recorded.According to the Pre-pregnancy BMI of the subjects,they were divided into 4 groups:low body weight group（BMI<18.5kg/m²）,normal body weight group（18.5kg/m²≤BMI<25.0kg/m²）,overweight group（25.0≤BMI<28.0 Kg/m²）and obesity group（BMI≥28.0kg/m²）;the weight gain of all subjects was calculated,and the P₂₅-P₇₅5 interval of weight gain was selected as the optimal GWG range of the study.Then,dividing the subjects into 3 groups according to the range:lower GWG group（less than optimal GWG）,normal GWG group（in the optimal GWG range）and the higher GWG group（more than optimal GWG）.Statistical analysis of pregnancy complications,delivery status,and neonatal birth status were performed using SPSS24.0.Results（1）Gestational weight gain has nothing to do with age,parity,etc.But it has a correlation with Pre-pregnancy BMI.There was a difference in the GWG of subjects in different BMI groups.The GWG was lower in the overweight and obese groups（F=1.270,P=0.007）.And the gestational weight gain in twin pregnancy was negatively correlated with the Pre-pregnancy BMI（correlation coefficient-0.228,P=0.000）.According to our study,it is more appropriate to control the GWG with twin pregnancies at 15.0-21.0kg.（2）The incidence of gestational diabetes mellitus（GDM）（P=0.002）and pregnancy with hypertension（P=0.003）in the overweight and obesity groups was higher than that in the other two groups.The incidence of anemia（P=0.031）and premature rupture of membranes（P=0.012）in the normal weight group was lower than that of the other three groups.Also,there was a difference in the incidence of pregnancy with hypothyroidism between 4 groups,but there is no statistical significance in the difference（P=0.180）.The average weight of newborns in the overweight and obese groups was higher than that of low body weight and normal body weight（F=2.187 P=0.010）,and the incidence of low birth weight infants was also lower than the other two groups（P=0.003）.And the average birth weight of newborns was positively correlated with Pre-pregnancy BMI（correlation coefficient was 0.115,P=0.011）.But,the incidence of asphyxia with overweight group was higher than the other two groups,and the difference has statistical significance（P=0.000）.The incidence of cesarean section rate（P=0.004）and postpartum hemorrhage（P=0.000）in the overweight and obese groups were higher than those in the low body weight and normal body weight.（3）The incidence of hypertensive disorder hypertensive disorder（P=0.009）,pregnancy with hypothyroidism（P=0.007）,pregnancy with anemia（P=0.005）,and premature rupture of membranes（P=0.004）were higher than the other groups.However,the incidence of gestational diabetes was highest in the group with lower GWG,and the difference was statistically significant（P=0.008）.The average birth weight of newborns in the lower GWG group was higher than that in the other two groups（F=3.940,P=0.008）.The average birth weight of newborns was positively correlated with their weight gain during pregnancy（correlation coefficient was 0.296,P=0.000）.And the incidence of premature infants（P=0.001）and low birth weight infants and neonatal asphyxia（P=0.002）in higher GWG group was lower than that of the other two groups.However,the incidence of cesarean section rate（P=0.004）and postpartum hemorrhage（P=0.000）in higher GWG group were higher than the other two groups.（5）In this study,the appropriate weight gain rate for twin pregnancies was0.39⁰.58kg/w.The slow rate of GWG is the factor of preterm birth[0R=1.71,95%CI（1.07 to 2.71）,P=0.004]and low birth weight infants[0R=1.38,95%CI（1.05 to1.82）,P=0.002].Excessive rate of GWG is the factor of gestational diabetes mellitus[0R=2.18,95%CI（1.56³.06）,P=0.000],hypertensive disorder complicating pregnancy[0R=2.99,95%CI（2.15⁴.15）,P=0.000].Conclusion Pre-pregnancy BMI and gestational weight gain are associated with maternal-fatal outcomes.The Pre-pregnancy and post-pregnancy weight management of twin pregnancies should be guided to reduce the risk of adverse pregnancy outcomes.