Association between amniotic fluid index at term and ultrasound estimation of fetal weight and actual birth weight: an observational cross-sectional study
Laxmi Umeshappa,Ashwini Harish Pai,Arpitha VJ,Aman James,Abijith KV,Mahesha
Objectives: To study the influence of amniotic fluid volume at term gestation with accuracy in fetal weight estimation by ultrasound. Methods: Retrospective observational cross-sectional study was done in 358 term deliveries over a period of two years from January 2019 to December 2020 in a medical college hospital. All singleton term pregnancies that had an ultrasound estimation of fetal weight and amniotic fluid within a week of delivery were included, irrespective of parity, age and mode of delivery. Error in estimation of fetal weight was calculated with reference to actual birth weight and comparisons were made to note the degree of accuracy across varying amniotic fluid volume by applying ANOVA and Tukeys test. Results: Mean error in fetal weight estimation was not significant with respect to parity index, gestational age or fetal gender. There was a significant (p= 0.001) increasing mean birth weight with increasing amniotic fluid volume and the error in estimation of fetal weight was significant across all AFI groups (p= 0.014). Mean error in oligoamnios group was significantly lesser than normal liquor (p=0.041) and high normal (p= 0.032) at a 5% level of significance. Hence, the estimation of fetal weight in the oligoamnios group was more accurate. Conclusion: Amniotic fluid volume and ultrasound fetal weight estimation are mostly independent variables though they are factors of gestational age. Consistent errors are seen across varying AFI. The noticeable accuracy in the low liquor group is reassuring as oligoamnios is frequently associated with low birth weight.