The Effect of Oligohydramnios on Estimated Fetal Weight Measurements in Term Pregnancies

Abstract

Objective: The role of amniotic fluid volume, as a potential factor that may affect the estimated fetal weight measurements remains controversial. The objective of our study was to investigate the effect of oligohydramnios on the accuracy of fetal weight estimation in term pregnancies with oligohydramnios. Method: The data of 207 pregnants diagnosed with oligohydramnios and 610 pregnants with a normal amniotic fluid volume in between January 2018 and June 2019 were compared retrospectively.Amniotic fluid volume and estimated fetal weight measurements were performed via ultrasonographic examination in all pregnants up to 48 hours before birth. Hadlock-4 Formula was used as the estimated fetal weight scale. After picking the estimated fetal weights and actual birthweights in two groups, absolute error, absolute error rates, rates of pregnancies with a higher and a lesser fetal weight estimations were compared. Results: The mean estimated fetal weights were 3.110 (550) g in Group 1 (oligohydramnios) and 3420 (665) g in Group 2 (normal amniotic fluid volume). The actual birth weights were 3.130 (620) g and 3.410 (660) g for Group 1 and 2, respectively. Both values in Group 1 were detected as lower significantly, when their estimated and actual fetal birthweights compared with Group 2. The error between estimated fetal weights and actual birthweights was 240 (160) g, error rate was 7.3% (4.5) in Group 1. The error and error rates were 230 (200)g and 6.9% (6.0) in Group 2, respectively. When the error and error rates compared in groups, any significant difference was not detected. Conclusion: There is no any relation between oligohydramnios and estimated fetal birthweight in term pregnancies.There seems a tendency to measure estimated fetal weights higher in oligohydramniotic pregnancies.

The Impact of the Active Stage of Labor on Estimate Fetal Weight: A Prospective Cohort Study

“…The number of cases included in the study was calculated as n=32 when the first type error level was α=0.05, the second type error level was β=0.20, and the power of the test was 80% according to the study "The Effect of Oligohydramnios on Estimated Fetal Weight Measurements in Term Pregnancies'' G*power analysis. 4 Definitions Estimated fetal weight measurement was calculated using Hadlock-4 formula, log10 EFW=1.3596-0.00386 (AC) x (FL) + 0.0064 (HC) + 0.00061 (BPD) x (AC) + 0.0424 (AC) + 0.174 (FL). Oligohydramnios diagnosis was defined as AFI less than 50 mm without fetal anomaly, while normal AFI value was defined as AFI values equal to or greater than 50 mm and AFI values equal to or less than 250 mm.…”