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Am J Perinatol 2014; 31(09): 745-752
DOI: 10.1055/s-0033-1359721
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Impact of Cervical Effacement and Fetal Station on Progress during the First Stage of Labor: A Biexponential Model

Maria M. E. Quincy
1   Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California
,
Chunhua Weng
2   Department of Biomedical Informatics, Columbia University, New York, New York
,
Steven L. Shafer
3   Department of Anesthesiology, Columbia University, New York, New York
,
Richard M. Smiley
3   Department of Anesthesiology, Columbia University, New York, New York
,
Pamela D. Flood
1   Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, California
4   Department of Obstetrics, Gynecology, and Reproductive Medicine, University of California, San Francisco, San Francisco, California
,
Fadi G. Mirza
5   Department of Obstetrics and Gynecology, American University of Beirut, Beirut, Lebanon
6   Department of Obstetrics and Gynecology, Columbia University, New York, New York
› Author Affiliations
Further Information

Publication History

28 August 2013

19 September 2013

Publication Date:
11 December 2013 (online)

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Abstract

Objective To develop a model that uses cervical effacement, fetal station, and parity to predict progress during the first stage of labor.

Study Design This was a secondary analysis of a cohort of 1,128 parturients delivering after 34 weeks. Timed cervical exams from each patient were fit with a biexponential model. Methods for consideration of fetal station, cervical effacement and parity were developed and validated.

Results The biexponential model fit the data in an unbiased manner with a median absolute prediction error of 1.1 cm. Although nulliparous women had slower active labor, they did not differ from multiparous women in their rate of latent labor or the cervical dilation at which they transitioned to active labor. In addition, nulliparous women began laboring with a more effaced cervix (45 vs. 31%) and lower fetal station (–2.8 vs. –3.2).

Conclusion We validated a biexponential model for labor progress using a large mixed parity cohort. We demonstrated that parity and initial fetal station add important clinical information that can be used to make a labor model more accurate. As such, parity and fetal station can be utilized in such structural models to predict normal labor progress and potentially identify abnormalities in labor progress.

Keywords

cervical dilation - cervical effacement - fetal station - labor - parity