Biophysical and biochemical markers at 35-37 weeks' gestation in the prediction of adverse perinatal outcome

Abstract

Objective: To investigate the potential value of biophysical and biochemical markers at 35-37 weeks' gestation in the prediction of adverse perinatal outcome.

Methods: This was a screening study in 3953 singleton pregnancies at 35-37 weeks' gestation. Estimated fetal weight (EFW), uterine artery pulsatility index (UtA-PI), umbilical artery (UA)-PI, fetal middle cerebral artery (MCA)-PI, mean arterial pressure (MAP), serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured. The detection rate (DR) and false-positive rate (FPR) of screening by each biomarker were estimated for pre-eclampsia (PE), delivery of small-for-gestational-age (SGA) neonates, Cesarean section for fetal distress before or during labor, umbilical arterial cord blood pH ≤ 7.0 or umbilical venous cord blood pH ≤ 7.1, 5-min Apgar score < 7 and admission to the neonatal unit (NNU).

Results: Multivariable regression analysis demonstrated that significant prediction of PE was provided by PlGF, sFlt-1 and MAP, with a DR of 73% at a 10% FPR. Prediction of SGA was provided by EFW, PlGF and UtA-PI, with a DR of 63% at a 10% FPR. Prediction of Cesarean section for fetal distress before labor was provided by EFW and UA-PI with DR of 100% at 10% FPR. Prediction of fetal distress in labor was provided by EFW and sFlt-1, with a DR of 15% at a 10% FPR. There were no significant differences between those with a normal outcome and those with low cord blood pH, low Apgar score or NNU admission for any of the biomarkers assessed.

Conclusion: At 35-37 weeks' gestation biomarkers of impaired placentation and fetal hypoxemia provide good prediction of PE, SGA and fetal distress before labor, but poor or no prediction of adverse events in labor or after birth.

Keywords: mean arterial pressure; middle cerebral artery Doppler; perinatal outcome; placental growth factor; pyramid of antenatal care; sFlt-1; third-trimester screening; umbilical artery Doppler; uterine artery Doppler.