Effect Of Body Mass Index On Birth Weight And Mode Of Delivery

Objective: To study the effect of body mass index (BMI) changes before and during pregnancy on birth weight and mode of delivery. We should try our best to reduce the cesarean section rate.Methods: 980 primigravidas delivered in the department of Obstetrics, the First Affiliated Hospital of Dalian Medical University from March 2009 to September 2010. The women were all full-term and singleton pregnancies, their average age were 29 years old. The study's date was complete, which removed the premature and postterm birth, multiple births, placenta previa, placental abruption. The retrospective and comparative analysis of cases recorded age, gestational age, height, weight before pregnancy and prenatal , birth weight, delivery mode and other parameters.The study based on the pre-pregnancy body mass index were divided into four groups:1 group was BMI<18.50 kg/m~2;2 group was BMI:18.50～24.00kg/m~2;3 group was BMI:24.01～28.00kg/m~2;4 group was BMI>28.00kg/m~2.And it based on the change of the pregnancy body mass index were divided into three groups,"A"group was△BMI<4.00kg/m~2;"B"was△BMI:4.00～6.00kg/m~2;"C"was△BMI>6.00kg/m~2. Group 2 and group B will be as the normal group.The normal groups were compared neonatal birth weight, gestational hypertension, Gestational Diabetes Mellitus, cesarean section rates with the other groups, they were statistically analyzed by SPSS17.0. We used the t test to analysis the measurement data and used the x2 test to analysis the count data, p <0.05 regarded as statistically significant. Meanwhile, we analyzed the BMI changes before and during pregnancy on birth weight and cesarean section rate, calculated p and r, r> 0, p <0.05 considered as being related to; r <0, p <0.05 was considered negative; the p> 0.05 considered as not relevant. Results: (1).The birth weight was statistically significant of the 1 group, 3 group, 4 group and 2 group according to the pre-pregnancy BMI (p<0.05), the macrosomia was statistically significant of the 3 group, 4 group and 2 group(p<0.05), the pre-pregnancy BMI was positively related to the birth weight(r=0.184,p<0.05);The cesarean section rate was statistically significant of the 3 group, 4 group and 2 group according to the pre-pregnancy BMI (p<0.05);The gestational hypertension disorders were statistically significant of the 4 group and 2 group according to pre-pregnancy BMI (p<0.05), and the Gestational Diabetes Mellitus were statistically significant of the 3 group and 2 group. (2).The birth weight was statistically significant of the A group, C group and B group according to the changes of the pregnancy BMI, but the macrosomia was not statistically significant, the changes of the pregnancy BMI was positively related to the birth weight(r=0.236,p<0.05); The cesarean section rate was statistically significant of the A group, C group and B group according to the changes of the pregnancy BMI (p<0.05); The gestational hypertension disorders and the Gestational Diabetes Mellitus were statistically significant of the A group, C group and B group (p<0.05).Conclusion: The body mass index (BMI) changes before and during pregnancy is important for the birth weight, mode of delivery and pregnancy outcome, Pre-pregnancy overweight and obesity and excessive weight gain during pregnancy easily lead to macrosomia, the maternal complications and cesarean section rate would increase. But if you gain low weight during pregnancy, you could increase the cesarean section rate and maternal complications too.