Introduction
Small for gestational age (SGA) neonates refers to those with a birthweight < 10th percentile for gestational age.(1) These infants are at increased risk for adverse outcomes(2, 3) and this condition appears to complicate pregnancies with preterm labor and preterm prelabor rupture of membranes more often than uncomplicated pregnancies.(4, 5) Therefore, the accurate prediction of SGA will assist in creating surveillance protocols to reduce such adverse outcomes.(6)
The prevalence of fetal growth restriction (FGR) varies according to the definition used. In the United States the most commonly used definition is an estimated fetal weight < 10thpercentile for gestational age, however this definition will most likely include those that are constitutional small.(7) Therefore, a new definition of FGR based on the Delphi criteria has been proposed by a group of international experts,(8) But a recent study found that the implementation of this definition was not associated with adverse outcomes when compared to the definition endorse by ACOG.(9)
The ability to detect SGA by the EFW, varies according the formula used to calculate the EFW and the fetal growth chart utilized to assign the EFW percentile according gestational age. (10-12)
The Hadlock et al(13) formula is the most commonly used method to calculate the EFW, as it appears to be an accurate predictor of the birtweight.(10)
Multiple studies have attempted to identify the most accurate fetal growth chart, and most of their results suggest that none of the recently developed charts appears to be superior to the Hadlock et al(14) growth chart in predicting SGA.(11, 15-17)
Despite the accuracy of the EFW to predict the birthweight, there is a discrepancy between fetal growth charts and neonatal growth charts, specially, in the preterm period.(18, 19) This lack of correlation is most likely due to the inclusion of multiple risk factors that are associated with both FGR and prematurity.(20) To solve this matter, the Fetal Medicine Foundation (FMF) developed a unified fetal and neonatal growth chart.(21) However, this chart has not been validated in specific obstetrical populations, such as PPROM.Thus, our aim was to compare the detection accuracy for SGA by the Hadlock fetal weight chart versus the Fetal Medicine Foundation (FMF) fetal and neonatal weight chart in pregnancies complicated by PPROM.