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CC-BY-NC-ND 4.0 · AJP Rep 2017; 07(01): e31-e38
DOI: 10.1055/s-0037-1599129
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Validation of a Prediction Model for Vaginal Birth after Cesarean Delivery Reveals Unexpected Success in a Diverse American Population

Authors

  • Melanie Mai Maykin

    1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, California
    2   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California

  • Amanda J. Mularz

    1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, California
    3   Department of Maternal-Fetal Medicine, Obstetrix Medical Group of Houston, Shenandoah, Texas

  • Lydia K. Lee

    1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, California

  • Stephanie Gaw Valderramos

    1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, California
    2   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California
Further Information

Publication History

28 July 2016

03 January 2017

Publication Date:
28 February 2017 (online)

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Abstract

Objective To investigate the validity of a prediction model for success of vaginal birth after cesarean delivery (VBAC) in an ethnically diverse population.

Methods We performed a retrospective cohort study of women admitted at a single academic institution for a trial of labor after cesarean from May 2007 to January 2015. Individual predicted success rates were calculated using the Maternal–Fetal Medicine Units Network prediction model. Participants were stratified into three probability-of-success groups: low (<35%), moderate (35–65%), and high (>65%). The actual versus predicted success rates were compared.

Results In total, 568 women met inclusion criteria. Successful VBAC occurred in 402 (71%), compared with a predicted success rate of 66% (p = 0.016). Actual VBAC success rates were higher than predicted by the model in the low (57 vs. 29%; p < 0.001) and moderate (61 vs. 52%; p = 0.003) groups. In the high probability group, the observed and predicted VBAC rates were the same (79%).

Conclusion When the predicted success rate was above 65%, the model was highly accurate. In contrast, for women with predicted success rates <35%, actual VBAC rates were nearly twofold higher in our population, suggesting that they should not be discouraged by a low prediction score.

Keywords

vaginal birth after cesarean - trial of labor after cesarean - MFMU VBAC calculator - VBAC success

Note

Presented in part in poster format at the 70th Annual Meeting of the Obstetrical and Gynecological Society of Southern California, May 8–9, 2015, Marina del Rey, California.