The relationship between the maternal body mass index and clinical fetal weight estimation in term pregnancy

Background: The correct fetal weight estimation is one of the factors influencing the safety of delivery. This study was aimed to examine the impact of maternal body mass index (BMI) on the accuracy of clinical fetal weight estimation.

Methods: 456 singleton pregnant women, with gestational age of 37 - 41 weeks were recruited according to the inclusion criteria of the study and were divided into four groups of body mass index. Then, the actual fetal weight and estimated clinical fetal weight were recorded. Finally, the collected data were entered into SPSS software (version 16). Pearson correlation coefficient and chi-square test were applied to analyze the relationship between the study variables.

Results: With an increase in maternal body mass index (BMI), age, weight and parity, the accuracy of clinical estimation of fetal weight was reduced. The estimation error in all four groups of BMI was mainly reported for higher estimation of weight, which was increased with an increase in BMI. In the BMI >30, the estimation accuracy of fetal weight was 70%, which indicated the worthiness of this method in estimating the fetal weight in all four groups.

Conclusion: Clinical estimation of fetal weight is a reliable method to be used for the mothers with varied BMI, although its accuracy is diminished with increased maternal BMI.