Methods
This study was a secondary analysis of a prospective cohort of pregnancies complicated by PPROM managed in our institution from October 2015 to June 2018.
The University of Tennessee Health Science Center Institutional Review Board approved our study protocol (XP15-04083).
Inclusion criteria included singleton pregnancies of mothers from 13-46 years of age, from 23-36+6 weeks of gestation, with an EFW within two weeks prior to delivery. We excluded pregnancies with complex fetal anomalies and those with fetal demise. PPROM was diagnosed by a combination of history, physical examination, biochemical, microscopic, and ultrasonographic findings. All included participants signed informed consent. Demographic and clinical characteristics including maternal age, parity, self-reported race, body mass index (BMI) at presentation, gestational age at PPROM, presence of hypertension, diabetes, chorioamnionitis, latency, gestational age at delivery, birthweight (BW) were extracted from maternal medical records. Neonatal outcomes such as the presence of respiratory distress (RDS), grade III- IV intraventricular hemorrhage (IVH), neonatal sepsis, necrotizing enterocolitis stage 2 and 3 (NEC), and neonatal death, were obtained from the infant electronic medical records.
The primary outcome of this study was to calculate and compared the diagnostic accuracy for neonatal SGA by the Hadlock and the FMF charts in our cohort.
SGA was suspected when the estimated fetal weight (EFW) was <10th percentile by the Hadlock and FMF charts (FGR). Neonatal SGA was diagnosed with a birthweight <10th percentile based on the Alexander et al(22) BW chart.
The secondary outcome was to compare the ability of FGR by both growth charts to predict a composite of severe neonatal outcomes (SNO) when at least one of the following were diagnosed: RDS, IVH, NEC, neonatal sepsis, and perinatal death.
We also calculated the rate accuracy of the FMF fetal growth chart to diagnosed SGA utilizing the proposed FMF neonatal birthweight chart. (23) The rate of SGA utilizing this approach was also obtained. In this study RDS was defined as having clinical and radiologic evidence of surfactant deficiency,(24) grade III and IV IVH was defined according to the Papille et al(25) classification, necrotizing enterocolitis stage 2 and 3 was defined according to Bell’s staging,(26) neonatal sepsis was confirmed with positive blood cultures, and perinatal death was comprised of deaths occurring from 20 weeks of gestation to the first year of life.
Ultrasound assessments were performed using a GE Voluson E8 by a maternal-fetal medicine fellow or an obstetrics and gynecology resident. The EFW was calculated every 2 weeks utilizing the Hadlock et al formula.(13)