BACKGROUND AND PURPOSE:

• Guidelines advise delivery at 37w0d (or at time of diagnosis if later) for preeclampsia without severe features 
• Chappell et al. (The Lancet, 2019) compared planned delivery vs expectant management (usual care) for late preterm (between 34 and 37 weeks) pre-eclampsia

METHODS:

• Parallel-group, non-masked, multicenter, randomized controlled trial
• Participants
  • 34w0d to 36w6d
  • Singleton or dichorionic diamniotic twin pregnancy
  • Diagnosis of preeclampsia or superimposed preeclampsia (per ISSHP guidelines)
• Exclusion: Plan to deliver based on current practice of immediate delivery for preeclampsia with severe features
• Groups (randomized)
  • Planned delivery (within 48 hours)
  • Expectant management (usual care)

Note: Algorithm used to balance certain features between groups such as study site, severity of BP, parity, previous cesarean and gestational age by week

• Data analysis
  • Intention to treat
  • Sample size 450 per group (assuming loss to follow-up): Calculated using a 25% risk reduction | 5% significance level | 90% power
• Primary outcome
  • Maternal: Composite of maternal morbidity or recorded systolic blood pressure of at least 160 mm Hg (superiority)
  • Perinatal: Composite of perinatal deaths or NICU admission up to infant hospital discharge (non-inferiority hypothesis)
• Secondary outcomes: Individual components of composite outcomes such as use of anti-hypertensives, progression to severe preeclmapisa etc.

RESULTS:

• 450 women planned delivery group | 451 women were in the expectant management group
• Planned delivery group
  • Only 2 women had spontaneous onset of labor
  • 73% initiated within 48 hours
• Expectant management
  • 54% had medically indicated delivery <37 weeks
  • Only 2 women delivered <37 weeks without a medical indication
• The incidence of the co-primary maternal outcome was significantly lower in the planned delivery group (mothers)
  • Planned delivery group: 65%
  • Expectant management group: 75%
  • Adjusted relative risk (RR) 0.86 (95% CI 0.79 to 0.94; p=0.0005)
• The incidence of the co-primary perinatal outcome was significantly higher in the planned delivery group (infants)
  • Planned delivery group: 42%
  • Expectant management group: 34%
  • Adjusted RR 1.26 (95% CI, 1.08 to 1.47; p=0.0034)
• Secondary outcomes
  • Adverse maternal component outcomes were also significantly lower in the planned delivery group (e.g, SBP ≥160 mm Hg, progession to severe preeclampsia)
  • Adverse perinatal component outcome was significantly higher in the planned delivery group specifically for NICU admission due to prematurity but no differences in need of oxygen, length of stay, RDS, hypoglycemia, jaundice, infection or SGA  
  • Spontaneous vaginal delivery significantly higher in expectant group (36%) vs planned delivery group (29%); RR 1.21| 95% CI, 1.04 to 1.41)
  • Gestational age at delivery was earlier by 5 days in the planned delivery group (252 days) vs the expectant management group (257 days)

CONCLUSION:

• Planned delivery for late preterm preeclampsia resulted in reduced maternal morbidity and severe hypertension vs expectant management
• NICU admissions were higher in the planned delivery group, but not associated with severe neonatal morbidities
• The authors suggest that risk and benefits should be discussed with patients and further state that 

In conclusion, our trial supports offering initiation of delivery in women with late preterm pre-eclampsia

Learn More – Primary Sources:

Planned early delivery or expectant management for late preterm pre-eclampsia (PHOENIX): a randomised controlled trial

Related ObG Topics:

ACOG SMFM Recommendations: When to Deliver Medically Complicated Pregnancies

Diagnosing Preeclampsia – Key Definitions and ACOG Guidelines

Deliver Low Risk Patients at 39 Weeks to Prevent Hypertensive Complications?