Planned early delivery or ‘wait and see’ for late preterm preeclampsia?

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Researchers from UK say that planned early delivery in mothers with late preterm preeclampsia may result in fewer maternal deaths. However, the findings-from a randomized controlled trial (RCT)-must be balanced against the potential increase in neonatal intensive care unit (NICU) admissions for prematurity.

The conclusions are from a report on the PHOENIX trial, which was published in The Lancet. A total of 901 women from 46 maternity units across England and Wales were enrolled in the parallel-group, non-masked, multicenter RCT. All had late preterm preeclampsia without severe features at 34 to 37 weeks’ gestation and a singleton or dichorionic diamniotic twin pregnancy. At the time of the trial, UK guidelines recommended immediate delivery of women with persistent severe preeclampsia, who therefore were ineligible. 

Recruitment was from September 29, 2014 to December 10, 2018 and the participants were randomized to planned delivery or expectant management (delivery at 37 weeks’ gestation or sooner, if dictated by clinical needs). The co-primary maternal outcome was a composite of maternal morbidity or recorded systolic blood pressure at least 160 mm Hg with a superiority hypothesis. The co-primary perinatal outcome was a composite of perinatal deaths or neonatal admission up to infant hospital discharge with a non-inferiority hypothesis. Analyses were by intention to treat, together with a per-protocol analysis for the perinatal outcome.

The women in the planned delivery group had a significantly lower incidence of the co-primary maternal outcome (65% vs. 75%; adjusted relative risk 0.86, 95% CI 0.79-0.94; P = 0.0005). Looking at the co-primary perinatal outcome, the authors found that incidence was significantly higher in the planned delivery group (42% vs 34%; 95% CI 1.26-1.08; P = 0.0034). Incidence of serious adverse events was similar in both groups: nine in women with planned delivery and 12 in those with expectant management. No stillbirths or neonatal deaths occurred in either group but there were more admissions to the NICU in the planned delivery group.

Compared with the expectant management group, the planned delivery group had lower maternal and infant costs that resulted in an adjusted cost savings of £1478 per delivery (95% CI 2354-605; P = 0.00094).

The authors said that the results of their trial “support offering initiation of delivery in women with late preterm preeclampsia. The trade-off of lower maternal morbidity and severe hypertension against higher neonatal unit admissions, albeit without additional respiratory or other morbidity, should be discussed with women with late preterm preeclampsia to allow shared decision making on timing of delivery.”