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Pre-eclampsia in Hospital: Early Induction or Expectant Management

A multi-centre randomised trial to determine whether delivery in women with pre-eclampsia between 34+0 and 36+6 weeks of gestation reduces maternal complications without short and long term detriment to the infant compared to expectant management and delivery at 37 weeks of gestation.


Total: 901

Target: 900

Recruitment to the Phoenix trial is closed. We would like to thank all the families and site staff who took part.

Diagram of the Phoenix trial - description below.

Diagram Description

This diagram is a schematic representation of the PHOENIX trial. It is divided into 3 stages: pre-intervention, intervention and post-intervention.

The pre-intervention stage is divided into 4 steps: confirmation of pre-eclampsia, assessment for eligibility, obtaining the woman's consent and then randomisation.

The intervention stage shows the 2 possible interventions that a woman in the trial might receive: either planned delivery or expectant management. The post-intervention stage shows that after discharge from hospital follow-up data will be collected at six month post-delivery and 2 years of (age corrected).


In the UK, 10-15% of pregnant women develop hypertension in pregnancy, and 2-8% pre-eclampsia. Pre-eclampsia is a multisystem disorder, characterised by placental and maternal vascular dysfunction which is associated with significant morbidity and mortality for the mother and infant. Adverse outcomes of pre-eclampsia include severe hypertension, stroke, renal and hepatic injury, haemorrhage, fetal growth restriction and even death.

Early delivery may be indicated to prevent maternal and infant morbidity. Standard management of pre-eclampsia involves close monitoring whilst taking into consideration the gestational age of the fetus, fetal well-being and rate of progression of maternal disease to instigate timely delivery if needed. When a diagnosis of pre-eclampsia is made at or beyond 37 weeks of gestation, it is currently recommended that delivery be induced, since maternal and fetal risks can be significantly reduced without any apparent added risk associated with the intervention.

The optimal time to instigate delivery to prevent morbidity when pre-eclampsia occurs between 34 and 37 weeks of gestation, without increasing problems related to infant immaturity or complications, remains unclear. Current management involves close surveillance and action only when evidence of impending serious morbidity becomes apparent (e.g. deteriorating maternal or fetal conditions). As this may be rapid or unexpected, routine delivery beyond 34 weeks' may be valuable.

This aim of this study is to remove the uncertainty about the timing of delivery in pregnancies affected by pre-eclampsia between 34 and 37 weeks of gestation.

Study Treatment

Women will be randomly allocated to either the planned delivery or the expectant management group.

Woman randomised to the planned delivery group will commence their delivery with minimal delay (with initiation of delivery within 48 hours of randomisation to allow for steroid use and neonatal cot availability). Woman randomised to the expectant management group will be delivered at 37 weeks of gestation or sooner as clinical needs dictate.

Recruitment Target

The recruitment target is 900 women over 36 months. Initially, the study will be piloted in 6 consultant-led maternity units and later rolled out to a total of 25 centres across the country, pending the success of the pilot phase.

The pilot phase will be run, over a period of 6 months to establish whether the procedures and assessments are conducive to achieving the recruitment and other objectives of the study.

General reference information

EudraCT No.:
REC Reference:
Clinical Trials Unit:
National Perinatal Epidemiology Unit CTU
Co-sponsored by Kings College London and Guy's & St Thomas' NHS Foundation Trust
NIHR Health Technology Assessment (HTA) Programme
Duration of Study:
March 2014 - February 2020

Co-ordination, Sponsorship and Funding

This multi-centre trial is co-ordinated from the National Perinatal Epidemiology Unit Clinical Trials Unit (NPEU CTU) at the University of Oxford and is co-sponsored by Kings College London and Guy's and St Thomas' NHS Foundation Trust. Funding is provided by the National Institute of Health Research (NIHR) Health Technology Assessment (HTA) programme.

Updated: Monday, 07 March 2022 11:24 (v21)