Abstract:

Background: Estimating fetal weight is crucial for making choices about when to deliver a baby and how to deliver it, especially in high-risk pregnancies. Because ultrasound is scarce in resource-constrained places, clinical methods have been employed as an alternative for predicting fetal weight; however, accuracy has never been evaluated locally. This study aimed to determine the comparison between the clinical and sonographic estimation of fetal weight in correlation with birth weight at Bugando Medical Centre in Mwanza Tanzania.

Methods: A hospital-based cross-sectional comparative study that involved 400 pregnant women with singleton pregnancies admitted for elective cesarean section, induction of labor or in the latent phase of labor was carried out at Bugando Medical Centre from August 2022 to July 2023. Pregnant women were explained about the purposes of the study and those who voluntarily agreed to consent and met the eligibility criteria were enrolled in the study. A pretested data collection tool was used to collect the participants' information including; sociodemographic and clinical characteristics, fetal weight was estimated clinically by using Dare’s formula and ultrasound (USS) by using Hadlock formula, and actual birth weight was measured within 1 hour after delivery. Analysis was done by using SPSS version 20 according to the objectives. Frequency and percentage were used to present categorical variables. Wilcoxon Signed Rank Test was used to find similarities and mean absolute error and mean absolute percentage error were used to find accuracy. P- Value of < 0.05 was considered significant.

Results: In this study, the mean age of the women was 29.13 years ± 5.34SD. The estimated mean weight of a baby was 3495.06gm±370.734SD and 3472.09gm±1771.682SD by Dare’s, and ultrasound methods respectively, and 3252.83gm±454.909SD of actual birth weight. The mean fetal weight estimation by Dare's Formula and birth weight differed statistically significantly (p<0.001). Additionally, there was a statistically significant difference between the estimated fetal weight from ultrasound and the birth weight (p=0.013). There were no statistically significant differences in accuracy in predicting fetal weight in normal birth weight and macrosomic babies. The clinical method was not accurate on detecting low birth weight babies with a sensitivity of (7.3%). Both clinical and ultrasound methods were positively correlated with the birth weight of the fetus after delivery (Pearson Correlation=0.7309 and 0.7685) respectively.

Conclusion and recommendation: The accuracy of ultrasound in fetal weight estimations was found to be higher compared to clinical method, furthermore, ultrasound showed to have more accuracy in estimating low birth weight babies than clinical method. However, there was no statistically significant difference between clinical method and ultrasound in estimating normal birth weight and macrosomic babies. Hence we recommend that in resource-constrained settings without access to ultrasound machines, clinical method might be used to estimate normal birth weight and macrosomic babies that can aid healthcare professionals in decision making.