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.