ORIGINAL ARTICLES 604 19 2017 Background: Two types of growth curves are commonly used to diagnose fetal growth disorders: neonatal birth weight (BW) and sonographic estimated fetal weight (EFW). The debate as to which growth curve to use is universal. Objectives: To establish sonographic EFW growth curves for the Israeli population and to assess whether the use of the BW growth curves currently adapted in Israel leads to under- diagnosis of intrauterine growth disorders. Methods: Biometric data collected during a 6 year period was analyzed to establish sonographic EFW growth curves between 15–42 weeks of gestation for the Israeli population. Growth curves were compared to previously published sonographic EFW growth curves. A comparison with the Israeli BW growth curves was performed to assess the possibility of under- diagnosis of intrauterine growth disorders. Results: Out of 42,778 sonographic EFW studies, 31,559 met the inclusion criteria. The sonographic EFW growth curves from the current study resembled the EFW curves previously published. The comparison of the current sonographic EFW and BW growth curves revealed under-diagnosis of intrauterine growth disorders during the preterm period. Four percent of the fetuses assessed between 26–34 weeks would have been suspected of being growth restricted; 2.8 percent of the fetuses assessed between 30–36 weeks would have been suspected of having macrosomia, based on the BW growth curves. Conclusions: New Israeli sonographic EFW growth curves re- semble previously published sonographic EFW curves. Using BW growth curves may lead to the under-diagnosis of growth disorders. We recommend adopting sonographic EFW growth to diagnose intrauterine growth disorders. IMAJ 2017; 19: 604–609 fetal growth disorder, birth weight (BW), estimated fetal weight (EFW), growth curves, Israel New Israeli Sonographic Estimated Fetal Weight Growth Curves as Compared to Current Birth Weight Growth Curves: On What Should Diagnosis of Intrauterine Growth Disorders Be Based? Alon Z. Sapir MD*, Izzat Khayyat MD*, Ron Rabinowitz MD, Arnon Samueloff MD, Lior Drukker MD and Hen Y. Sela MD Department of Obstetrics and Gynecology, Sonography Unit for Maternal and Women’s Health, Shaare Zedek Medical Center, affiliated with the Hebrew University Hadassah Medical School, Jerusalem, Israel ABSTRACT: KEY WORDS: *The first and second authors contributed equally to this study O bstetric ultrasound is an accepted practice and is per- formed frequently throughout pregnancy [1]. Sonographic estimated fetal weight (EFW) is used as a critical diagnostic tool for identifying fetal growth acceleration and restriction. Intrauterine growth restriction (IUGR) and suspected macro- somia are associated with poor obstetrical outcome and may impact pregnancy management. When IUGR or macrosomia are suspected, underlying causes for these conditions should be investigated. Second trimester IUGR may be associated with chromosomal abnormalities and both conditions are associated with preterm delivery, low Apgar score, gestational diabetes, adverse cognitive and behavioral outcomes, and intrauterine fetal death [2,3]. Sonographic EFW is based on biometric measurements such as biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femoral length (FL). Several formulas have been published to improve estimation of fetal weight, yet no formula has been shown to be statistically superior to the one published by Hadlock in 1985 [4]. Following EFW calculations, the result is compared to an established fetal growth curve to assess whether the specifc fetus is within the normal range. Fetal growth varies among populations and is associated with geographic distribution and ethnicity [5]. Two types of growth curves are commonly used; neonatal birth weight (BW) growth curves and sonographic EFW growth curves. Over the years, numerous EFW and BW growth curves have been published for diferent populations [6,7]. Evidence shows that growth restriction is related to preterm delivery. Terefore, applying neonatal BW growth curves can cause under-estimation of IUGR in preterm infants [5,8-11]. Te debate as to which growth curve to use is universal. Te American College of Obstetrics and Gynecology defnes fetuses sufering from IUGR as those smaller than the 10th percentile of either sonographic EFW or BW, while the French College of Gynecologists and Obstetricians is against using BW growth curves and recommends using sonographic EFW growth curves [1,12].