Fetal Weight Estimation using Symphysio-fundal Height and Abdominal Girth Measurements in Different Pre-pregnancy Body Mass Indices

Abstract

Objectives: To study the accuracy of birth weight estimations obtained by multiplying the symphysio-fundal height (SFH) and abdominal circumference (AC) in different pre-pregnancy body mass index (BMI).Materials and Methods: This cross-sectional study was conducted from April 2015 to September 2015 at two tertiary hospitals. The authors included pregnant women with singleton fetus in vertex presentation with gestational age of 24-42 weeks and intact membranes who expected to deliver within 24 hours after admission. Participants were classified into four pre-pregnancy BMI categories using the criteria for Asian populations. The trained nurses in each hospital measured fundal height starting from the upper border of the symphysis pubis to tip of the uterine fundus, and then the AC was measured at the umbilical level using a measuring tape marked in centimeters. The procedure was conducted during no uterine contraction.Results: This study recruited 432 pregnant women. Spearman correlation coefficients between fetal weight obtained from multiplication of SFH and AC and actual birth weight in the underweight, normal weight, overweight and obese groups were 0.44, 0.54, 0.59, 0.71, respectively. There was no significant impact of pre-pregnancy BMI on the accuracy rate of birth weight estimation after adjusted for maternal age, parity, and gestational age.Conclusion: Pre-pregnancy BMI did not significantly affect the accuracy of fetal birth weight estimations obtained by multiplying SFH and AC.

Keywords

• fetal weight estimation
• abdominal circumference
• fundal height
• pre-pregnancy body mass index