The effect of pre pregnancy body mass index (BMI) and intrapregnancy weight gain on the pregnancy outcome among primigravida : a cross sectional study at Hospital Tengku Ampuan Afzan Kuantan

Abstract

The aim of the study was to measure the maternal and neonatal outcome among primigravida as per body mass index (BMI).This study also aimed to determine the optimal intra pregnancy weight gain which is associated with good outcome. This was a cross sectional study on primigravida who delivered at Hospital Tengku Ampuan Afzan between December 2011-June 2013. The study population include primigravida who booked <14 weeks gestation. Mother with multiple pregnancy, underlying medical problem such as hypertension or diabetes mellitus before pregnancy and no BMI data available at booking were excluded .The women were categorized into five groups according to their BMI (WHO classification): underweight (BMI? 19.9kg/m2), normal (BMI of 20-24.9kg/m2), overweight (BMI of 25-29.9kg/m2),obese (BMI of 30-34.9kg/m2)and morbidly obese (BMI >35kg/m2).The group with normal BMI was used as a reference or comparison group for the analysis. Data were analyzed using statistical package SPSS version 18.Chi-square (?2), independent t-test, one-way ANOVA and simple logistic regression were performed and p-value of <0.05 considered as statistically significant. Total of 500 women were enrolled which comprise of 130 (26%) underweight, 184 (36.8%) normal,100 (20%) overweight, 53 (10.6%) obese and 33 (6.6%) morbidly obese. Overweigth, obese and morbidly obese group had increased risk of gestational diabetes mellitus with the odd ratio of {OR2.199(1.111,4.352)}, {OR3.755(95%CI 1.766,7.986)} and {OR3.776 (95%CI 1.564,9.114)} respectively. There were increased risk of gestational hypertension {OR 1.965 (95%CI 1.007,3.836)} for overweight, {OR 2.272 (95%CI 1.034,4.994)} for obese and {OR 5.719 (95% CI 2.503,13.070)} for morbidly obese women. Underweight group had a protective effect against gestational hypertension {OR 0.308(95%CI 0.113,0.839)}.Preterm delivery was highest in the underweight women {OR2.038(95%CI 1.158,3.586)}.Induction of labour were high for the overweight, obese and morbidly obese women with odd ratio of {OR 1.945(95%CI 1.128,3.354)}, {OR 2.440 (95%CI 1.268,4.693)} and {OR 2.417(95%CI 1.105,5.286)} respectively. Morbidly obese women had increased risk of caesarean section {OR 2.339(95%CI 1.086, 4.993)}.Underweight women had significantly lower risk of caesarean delivery {OR 0.616(95%CI 0.379, 1.001)}. Women who are overweight, obese and morbidly obese also had higher incidence of augmentation of labour as well as wound infection. As per neonatal complication, underweight women faced higher risk of low birth weight baby {OR 1.801(95%CI 1.055, 3.076)}. Women who were overweight and obese had significantly low risk for low birth weight {OR 0.458(95%CI 0.081,0.934)} and {OR 0.275(95%CI 0.081,0.934)} respectively. As for macrosomia, morbidly obese women had higher incidence compared to normal BMI women. Thirty five percent of the women had reached the recommended intrapregnancy weight gain by Institute of Medicine (IOM) and there was no statistically significant association between intrapregnancy weight gain and pregnancy outcome. High pre pregnancy BMI is associated with increased maternal risk of gestational diabetes mellitus, gestational hypertension, induction and augmentation of labour, caesarean delivery and macrosomic babies. However the underweight women are associated with poor perinatal outcome namely preterm labour and low birth weight baby. Intrapregnancy weight gain does not influence the pregnancy outcome.