Amniotic Fluid Index Curves in the Obese Gravida: One Size Fits All? [36P]. (May 2018) - Chishom, Taylor
Abstract : INTRODUCTION: The purpose of this study was to evaluate whether amniotic fluid index (AFI) curves differed based on maternal body mass index (BMI) category. METHODS: This was a retrospective cohort study of 500 pregnant women receiving ultrasounds with AFI measurements. The study cohort was subdivided by maternal intake BMI into three groups: normal weight (18.5-24.9), overweight (25.0-29.9) and obese (>30). Demographic and outcome data were evaluated with chi square for dichotomous variables and ANOVA or Kruskal-Wallis on continuous variables as appropriate. Linear regression was used to evaluate AFI over gestation in each group and analysis of covariance was used to evaluate AFI over gestation between groups. RESULTS: There was no correlation between AFI and gestational age in each group (normal weight (R=.055), overweight (R=.161), obese (R=.018) or as an aggregate (R=.06)). However, there was a difference in AFI over gestation between groups (F (2, 1740) = 9.96, P<.001). Both, pre-existing diabetes (P=.002) and chronic hypertension (P<.001), were more prevalent in obese gravida. Obese gravida were more likely to develop gestational diabetes (P<.001). Development of pregnancy hypertensive disorders did not vary between BMI groups (P=.145). Mean gestational age of delivery was similar between groups (P=.266); however, infant birth-weight increased with increasing maternal intake BMI (P=.040). CONCLUSION: In this cohort, there is a difference in AFI based on maternal BMI when accounting for gestational age. While the absolute difference in our cohort was small, this finding suggests we should evaluate this question on a larger scale and potentially re-visit a "one size fits all" approach to AFI.