Association Between Features of Spontaneous Late Preterm Labor and Late Preterm BirthFunding This study was supported by grants (HL098554 and HL098354) from the NHLBI, by grants (HD21410, HD27915, HD27917, HD27869, HD34116, HD34208, HD40485, HD40500, HD40512, HD40544, HD40545, HD40560, HD53097, HD53118, HD68268, HD68258, HD68282, and HD36801) from the NICHD, and by a grant (UL1 TR000040) from the National Center for Advancing Translational Sciences, National Institutes of Health. The views expressed in this article are those of the authors and do not necessarily represent the views of the National Institutes of Health.
29 March 2019
19 July 2019
17 September 2019 (online)
Objective This study aimed to evaluate the association between clinical and examination features at admission and late preterm birth.
Study Design The present study is a secondary analysis of a randomized trial of singleton pregnancies at 340/7 to 365/7 weeks' gestation. We included women in spontaneous preterm labor with intact membranes and compared them by gestational age at delivery (preterm vs. term). We calculated a statistical cut-point optimizing the sensitivity and specificity of initial cervical dilation and effacement at predicting preterm birth and used multivariable regression to identify factors associated with late preterm delivery.
Results A total of 431 out of 732 (59%) women delivered preterm. Cervical dilation ≥ 4 cm was 60% sensitive and 68% specific for late preterm birth. Cervical effacement ≥ 75% was 59% sensitive and 65% specific for late preterm birth. Earlier gestational age at randomization, nulliparity, and fetal malpresentation were associated with late preterm birth. The final regression model including clinical and examination features significantly improved late preterm birth prediction (81% sensitivity, 48% specificity, area under the curve = 0.72, 95% confidence interval [CI]: 0.68–0.75, and p-value < 0.01).
Conclusion Four in 10 women in late-preterm labor subsequently delivered at term. Combination of examination and clinical features (including parity and gestational age) improved late-preterm birth prediction.
This study was presented as a poster at the 38th Annual Pregnancy Meeting, Society for Maternal-Fetal Medicine, February 1 to 3, 2018, Dallas, TX.
* Additional members of this network are listed in Appendix A.
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