Detection of small for gestational age in preterm prelabor rupture of
membranes by Hadlock versus the Fetal Medicine Foundation growth charts:
a prospective cohort study
Abstract
Objectives: Small for gestational age (SGA) neonates are at increased
risk for adverse outcomes, which is also common in pregnancies with
preterm prelabor rupture of membranes (PPROM). The primary outcome was
to compare the diagnostic accuracy for neonatal SGA by the Hadlock and
the FMF charts in our cohort, followed by the ability to predict
composite severe neonatal outcomes. Methods: This study was a secondary
analysis of a prospective cohort of pregnancies with PPROM from 2015 to
2018, from 23 to 36 completed weeks of gestation. Sensitivity,
specificity, and positive and negative predictive values were compared
as well as receiver operating curves (AUC). Results: Of the 106 women
who met inclusion criteria, 48 (45%) screened positive with the FMF
fetal growth chart and 22 (21%) screened positive with the Hadlock
chart. SGA was diagnosed in 12 infants (11%). Both fetal growth charts
had a comparable diagnostic accuracy and were statistically significant
predictors of SGA, Hadlock: AUC: 0.76, RR 7.6 95% CI (2.5- 23), FMF:
AUC: 0.76 RR 1.8-13.3 95% CI (1.8 – 99.3). Both growth standards were
poor predictors of severe neonatal outcomes. Conclusion: The Hadlock and
the FMF fetal growth charts are accurate predictors of SGA in
pregnancies complicated by PPROM. The FMF fetal growth chart may result
in a two-fold increase of positive screens, potentially increasing fetal
surveillance. We acknowledge the need for more diverse studies to
corroborate our results and identify the optimal fetal growth standard
to detect SGA and severe neonatal outcomes in pregnancies with PPROM.