BACKGROUND AND PURPOSE:

• Improved prediction models could help identify which women with late preterm labor will progress to delivery
• Glover et al. (Amer J Perinatol, 2019) identified risk factors that are associated with late-preterm delivery in women with spontaneous late-preterm labor

METHODS:

• Secondary analysis of Antenatal Betamethasone for Women at Risk for Late Preterm Delivery (ALPS) RCT (MFMU study)
• Participants
  • Singleton pregnancies at 34w0d to 36w5d (betamethasone vs placebo)
• Late preterm definition: 34w0d to 36w6d
• Groups
  • Women who delivered at term
  • Women who delivered preterm
• Data analysis
  • Optimal sensitivity and specificity of initial cervical dilation and effacement at predicting preterm birth were determined
  • Multivariable regression was used to identify factors associated with late preterm delivery

RESULTS:

• 732 women with late preterm labor | 431 (59%) delivered preterm
• Cervical dilation ≥ 4 cm for prediction of late-preterm delivery
  • 60% sensitivity | 68% specificity
  • AUC = 0.64 (95% CI, 0.61–0.68)
• Cervical effacement ≥ 75% for prediction of late-preterm delivery
  •  59% sensitivity and 65% specificity
  • AUC = 0.62 (95% CI, 0.58–0.65)
• Factors associated with late preterm delivery
  • Earlier gestational age at randomization: adjusted Odds Ratio (aOR) 0.8 (95% CI, 0.6 to 1; p=0.02)
  • Nulliparity: aOR 1.7 (95% CI, 1.1 to 2.6; p=0.01)
  • Fetal malpresentation: aOR 6.5 (95% CI, 0.8-53.6; 0.08)
• Combining clinical and examination features significantly improved late preterm birth prediction
  • 81% sensitivity | 48% specificity
  • AUC = 0.72 (95% CI, 0.68–0.75; <0.01)

CONCLUSION:

• 60% of women who experienced spontaneous late preterm labor will go on to deliver preterm
• A combined analysis of examination and clinical features (e.g. gestational age, cervical dilation) improved the accuracy of late-preterm birth prediction but “overall models remained only modestly predictive”

Learn More – Primary Sources:

Association Between Features of Spontaneous Late Preterm Labor and Late Preterm Birth

Related ObG Topics:

Does Shortened Midtrimester Cervical Length Predict Preterm Birth?

The QUiPP Predictive Algorithm and Impact on Treatment for Preterm Birth

Does Cervical Length Actually Predict Preterm Birth?