DEVELOPING A NEW FORMULA FOR ESTIMATING BIRTH WEIGHT AT TERM PREGNANCY
H. Risanto Siswosudarmo
Department of Obstetrics and Gynecology, Faculty of Medicine
Universitas Gadjah Mada/ Sardjito Hospital Jogjakarta
ABSTRACT
Background: Estimated birth weight (EFW) is used as a guidence for management of labor. Several methods are used from abdominal palpation, measurement of fundal height and ultrasound examination. For the shake of simplicity fundal height measurement to be the simplest and cheapest way that can be done by all medical personnels.
Objective of study: To develop a new formula in determining estimated birth weight based on maternal symphisis fundal height (FH).
Material and method: A cross sectional study was used, consisting of 655 pregnant women from Sardjito and affiliated hospitals at 37-42 weeks of gestation. Fundal height was measured from the symphisis to the top of uterine fundus, using inverted unelastic flexible tape. Infant birth weight (IBW) was determined by the same baby scale after calibrated. Linear regression analysis was used to calculate the correlation and develop the formula.
Result: A total of 655 pregnant mothers meeting the inclusion criteria from 37 to 42 weeks of gestation were recruited. Most of them were between 20 to 30 years old and their parity were almost comparable. The mean FH was 31.25 ± 2.35 cm (ranged between 24 to 38 cm) and the mean IBW was 3021.60 ± 341.14 grams (ranged between 2050 to 4250 grams). The Pearson correlation was 0.93 (R square 0.86), signifying that there was a strong correlation between FH and IBW. The formula for estimating IBW based on FH was Y (IBW in gram) = 125 X (FH in cm) – 880.
Conclusion: There was a strong correlation between FH and IBW. The formula for estimating IBW was IBW = 125 FH – 880.
Key words: Estimating birth weight, Fundal height, Actual birth weight, Risanto’s formula.