BACKGROUND AND PURPOSE:

• Early-term period (37 weeks–38 weeks) associated with higher risks than term (39–41 weeks)
• Studies often combine births at 37 and 38 weeks
• Eskes et al. (BJOG, 2019) assessed neonatal mortality and morbidity risk by separating out 37 weeks specifically

METHODS:

• Nationwide cohort study
  • Data from the national perinatal registry (PERINED) that covers 99% of deliveries in the Netherlands
• Participants
  • Singleton delivery at term (37w0d – 41w6d) | No congenital malformations | 5-year period (2010-2015)
• Primary outcomes
  • Mortality (definition): Intrapartum or neonatal mortality during the first 4 weeks of life
  • Adverse neonatal outcome (definition): ≥1 of the following
    • Neonatal mortality
    • Low 5-minute Apgar score (<7)
    • NICU admission
• Data and analysis
  • 37 week group compared to 39-41 week group
  • Odds ratio (OR) adjusted for: Parity | Age | Ethnicity | Socio-economic status | Hypertensive disordere | SGA (<10^th BW centile)
  • Logistic regression to assess indication and mode of delivery

RESULTS:

• 755,198 women were included
• Neonatal mortality was higher at 37 weeks (1.10%) vs 39-41 weeks (0.59%) (P < 0.0001)
  • Adjusted OR 1.84 (95% CI 1.39–2.44)
• Adverse neonatal outcomes were more likely at 37 weeks (21.4%) vs 39-41 weeks (12.04%) (P < 0.0001)
  • aOR 1.63 (95% CI 1.53–1.74)
• Spontaneous start of labor at 37 weeks was associated with increased neonatal mortality
  • aOR 2.20 (95% CI 1.56–3.10)
  • Risk not influenced by primary (midwifery) vs specialist care
  • Risk was specific to spontaneous start of labor and not influenced by induction or planned cesarean

CONCLUSION:

• Birth at 37 weeks are independently associated with a higher frequency of adverse perinatal outcomes than birth at 39-41 weeks
• The authors recommend for intensive monitoring during labor for this group and state

Our findings provide a reason to regard the start of labour at 37 weeks of gestation not as low risk but as an intermediate group between preterm and term birth with clearly elevated perinatal risk.

Learn More – Primary Sources:

The risk of intrapartum/neonatal mortality and morbidity following birth at 37 weeks of gestation: a nationwide cohort study

Related ObG Topics:

Does Extending Pregnancy Beyond 39 weeks in Low-Risk Pregnancies Incur Additional Risk?

Is the Change in Gestational Age Distribution in the US Having an Effect on Perinatal Mortality?

Delivery at 37 or 39 Weeks for Higher Order Cesarean Sections?