Evaluating the correlation between amniotic fluid volume and estimated fetal weight in healthy pregnant women

Objectives: The establishment of cut-offs for normal amniotic fluid volume (AFV) is valuable to predict perinatal outcomes. However, the most common methods to measure AFV are not accurate enough. It is important to understand factors that may be able to increase the accuracy of the calculation of AFV cut-off values. The objective of this study was to verify the correlation between AFV and estimated fetal weight (EFW).

Methods: Records from almost 7,000 patients between 2012 and 2017 were accessed through hospital databases. The AFV measurements included in our analysis were obtained using the maximum vertical pocket technique.

Results: AFV was positively correlated with EFW in the overall, male and female samples; however, the magnitude of the association was small (0.1<r<0.3). A moderate (0.3≤r<0.5) association between AFV and EFW was found specifically during mid- to late-gestation.

Conclusions: The incorporation of EFW together with other factors (e.g., gestational age, fetus sex) may increase the accuracy of the AFV cut-offs calculation and, ultimately, reduce morbidity.