Chappell LC, Brocklehurst P, Green ME, et al; PHOENIX Study Group. Planned early delivery or expectant management for late preterm pre-eclampsia (PHOENIX): a randomised controlled trial. Lancet. 2019;394:1181-1190.
Preeclampsia is a common hypertensive disorder of pregnancy. Among women who develop the disease at late preterm gestation, the question remains, “What is the optimal timing for delivery?” The American College of Obstetricians and Gynecologists (ACOG) categorizes preeclampsia as “with and without severe features.”1 Delivery is recommended for women with preeclampsia with severe features at or beyond 34 weeks’ gestation, and for women with preeclampsia without severe features at or beyond 37 weeks’ gestation.1 For patients with fetal growth restriction and preeclampsia, ACOG also recommends delivery between 34 and 37 weeks’ gestation.
Details of the study
Chappell and colleagues conducted a randomized controlled trial among women with singleton or dichorionic diamniotic twin pregnancy between 34 and 36.6 weeks’ gestation. Women were assigned to either planned delivery within 48 hours of randomization or expectant management until 37 weeks or earlier with clinical deterioration.
Among the 901 women included in the study, 450 were allocated to planned delivery and 451 to expectant management.
Study outcomes. The co-primary short-term maternal outcome was a composite of maternal morbidity with the addition of recorded systolic blood pressure of at least 160 mm Hg postrandomization (on any occasion). The co-primary short-term perinatal outcome was a composite of neonatal deaths within 7 days of delivery and perinatal deaths or neonatal unit admissions.
Participant details. At baseline, the average gestational age at randomization was 35.6 weeks, with equal distribution through the 3 weeks (34 through 36 weeks). About 37% of the women had severe hypertension (≥ 160 mm Hg) in the previous 48 hours prior to randomization, and approximately 22% had fetal growth restriction. The authors did not categorize the women based on severe features of preeclampsia.
Results. The investigators found that the proportion of women with the maternal co-primary outcome was significantly lower in the planned delivery group compared with the expectant management group (65% vs 75%), and the proportion of infants with the perinatal co-primary outcome was significantly higher in the planned delivery group compared with the expectant management group (42% vs 34%). The fact that early delivery led to more neonatal unit admissions for the infant, principally for a listed indication of prematurity and without an excess of respiratory or other morbidity, intensity of care, or length of stay, is very reassuring.
Study strengths and limitations
This is the largest study of women in this group allocated, randomized, and multicenter investigation addressing a very important clinical question. The patient population was mostly white, with only 13% black women, and had an average body mass index of 29 kg/m2 (which is low compared with many practices in the United States). The average difference between the 2 study groups was the additional prolongation of pregnancy from enrollment to delivery of only 3 days, which may not be clinically relevant. More than half of the women in the expectant management group had medically indicated delivery before 37 weeks’ gestation.
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