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.