Introduction
Pre-eclampsia affects around 2-3% of all pregnancies,(1) and is associated with potential serious complications for the woman and baby, including multiple maternal organ dysfunction (severe hypertension, renal and liver impairment, abnormal clotting and stroke/ seizures) and fetal morbidity and mortality. Once diagnosed, progression of the syndrome can be unpredictable, and decisions around timing of delivery needs to take into account evolving maternal complications and perinatal morbidity. We have recently completed the multicentre PHOENIX trial, in which we demonstrated that in women with late preterm pre-eclampsia, planned delivery reduces maternal morbidity, whilst increasing neonatal unit admissions (principally for prematurity as the indication), though with no difference in neonatal morbidity (including respiratory distress), compared with expectant management.(2) Of women in this gestational age window (34 to 37 weeks of pregnancy) managed expectantly, over half required delivery for clinical indications before they reached 37 weeks’ gestation, and pregnancy was prolonged (compared to planned delivery) by three days only.
Current parameters advised by national guidelines for indicating need for delivery in pre-eclampsia are relatively blunt: e.g. uncontrolled severe maternal hypertension, abnormal maternal haematological/ biochemical indices or fetal compromise on ultrasound or cardiotocography.(3) Novel prognostic models and blood biomarkers for determination of need for delivery in pregnancies with pre-eclampsia are now emerging,(4, 5) but their applicability to contemporaneous populations of women with confirmed late preterm pre-eclampsia needs further evaluation and validation. Existing clinical models, such as those from the Prediction of complications in early-onset pre-eclampsia (PREP) study accurately predict the risk of complications in women with early onset pre-eclampsia before 34 weeks’ gestation (PREP-S) and have now been included in UK national guidelines.(3) If accurate, these models and blood markers in women with late preterm pre-eclampsia could potentially enhance the ability of clinicians and women to determine who is at greatest risk of need for delivery, enabling timely surveillance and decisions around use of antenatal corticosteroids or place of care.
The aim of the study was to establish a prognostic model to inform optimal timing of delivery in women with late preterm pre-eclampsia (34+0 to 36+6 weeks’ gestation), comparing novel candidate biomarkers including plasma placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1):PlGF ratio with clinical and routinely collected blood/ urinary parameters to determine clinically indicated need for delivery for pre-eclampsia (or its related complications) within seven days of assessment.