The Association Between Ultrasonic Estimated Fetal Weight and Neonatal Weight
Author(s): Ahmad Enhesari, Farnaz Fahimi, Hamed Tahmouresi
Predicting neonatal birth weight based on fetal parameters assessed by the ultrasonography has been suggested and thus an association between fetal weight and neonatal weight has been hypothesized. The present study aimed to determine the value of ultrasound fetal weight estimation for predicting birth weight. We also discovered an equation between fetal weight estimated by ultrasonography and birth weight. This cohort study was performed on 125 singleton pregnant women with the gestation of 39 weeks and healthy fetus that referred to our hospital due to receive prenatal cares. The Fetal biparietal diameter measurements were obtained simultaneously by gray scale and bistable ultrasonography and then the fetal weight was estimated using the hadlock formula. After birth, all neonates were weighted using a single calibrated balance. There was a strong association between ultrasonic fetal weight before delivery and neonatal birth weight (r coefficient 0.875, p < 0.001). Based on the area under the ROC curve (AUC) analysis, estimating ultrasonic fetal weight had high value for predicting LBW (AUC = 0.936, 95%CI: 0.865 – 1.008, P < 0.001). In this regard, the best cutoff point of ultrasonic fetal weight to discriminate LBW from normal weight was 2725 gr yielding a sensitivity of 92.9% and a specificity of 83.3%. Assessing the linear association between ultrasonic fetal weight and birth weight led to obtain the following equation to estimate neonatal birth weight: BW = 0.97 × UFW + 144.82. Due to strong association between ultrasonic estimated fetal weight and birth weight and thus by ultrasonic determination of fetal weight, early prediction of neonatal-related weight abnormalities such as LBW can be possible.