Early prediction of birth weight percentile and large for gestational age fetuses using gestation-adjusted projection of estimated fetal weight

Lim, Young Goo; Kim, Se Ryun; Oh, Gwan Young; Park, Jee Hyun; Noh, In Hwa; Song, Eun Sub; Lim, Moon Hwan; Lee, Byung Ik; Kim, Jong Hwa; Lee, Woo Young

Abstract

OBJECTIVE
To evaluate the accuracy of predicted birth weight percentile and large for gestational age(LGA) fetuses by the gestation-adjusted projection method using estimated fetal weight. METHODS: From 462 low-risk pregnancies with singleton fetus, fetal biometry including fetal biparietal diameter(BPD), head circumference(HC), abdominal circumference(AC), and femur length(FL) was made from 30 weeks of gestation until term. Estimated fetal weight(EFW) by combinations of fetal biometry were made by Campbell, Hadlock1, Hadlock2, and Shepard formulas respectively. The diagnostic accuracy according to 4 formulas was assessed by correlation between EFW percentile and birth weight percentile, prediction of LGA fetuses, and prediction error(percentile difference between birth weight and EFW). RESULTS: The mean gestational age on ultrasound and on birth, and birth weight were 33.21 +/- 2.08(30-40) weeks, 38.43 +/- 1.72(30-42) weeks, and 3.14 +/- 0.47(0.99-4.38) Kg, respectively. The diagnostic accuracies of gestation-projection method using EFW were similar result to predict birth weight percentile and LGA fetuses according to 4 formulas. Correlation between EFW percentile and birth weight percentile(correlation coefficient, r) were Campbell: 0.644(p <0.001), Hadlock 1: 0.682(p <0.001), Hadlock 2: 0.681(p <0.001), Shepard: 0.638(p <0.001), respectively. Youden's index(sensitivity + specificity - 1) in prediction of LGA fetuses were Campbell: 0.532, Hadlock1: 0.525, Hadlock2: 0.520, Shepard: 0.549, respectively. Prediction error were Campbell: 18.14+/-16.56, Hadlock1: 16.19+/-14.35, Hadlock2: 16.10+/-14.29, Shepard: 19.68+/-17.00, respectively. The prediction error was increased according to increasing of lapse time(p <0.001), gestational weeks on ultrasound, and estimated fetal weight percentile, and decreasing birth weight percentile(p <0.001)(R square=0.411, (p <0.001). But, amniotic fluid index did not affect to prediction error(p=0.199). CONCLUSION: Our study presented relatively accurate prediction for birth weight percentile and LGA fetuses from remote sonographic examination. If LGA fetuses was suspected by antenatal ultrasound, adequate therapy and periodic observation are recommended for good perinatal outcome.