First stage of labor models show promise in predicting complications

1. Adaptive multifactorial models for dilation and station percentile showed better discrimination for cesarean delivery outcomes compared to traditional duration of arrest when dilation ≥ 6cm.

2. Mathematical models for station percentile were able to discriminate for obstetric hemorrhage and neonatal depression.

Evidence Rating Level: 2 (Good)

Study Rundown: Protraction and arrest of labor are common indications for cesarean delivery (CD) and can be secondary to uterine, fetal, and pelvic anatomical factors. The first stage of labor is the time between onset of labor and complete cervical dilation. Labor is divided into the latent phase, in which cervical changes are gradual, and the active phase, in which cervical changes occur more rapidly. Historically, the transition to the active phase was thought to occur at about 4cm dilation and a rate of cervical change of 1cm/hr for nulliparous women and 1.2cm/hr for parous women, respectively, were established. Newer studies demonstrate that at less than 6cm dilation, many women dilate at a rate < 1cm/hr and still go on to have uncomplicated vaginal deliveries. Using an adaptive multifactorial model, researchers have previously demonstrated that expected dilation and station curves that can be appropriately individualized to the patient. In the present work, the authors compared this model with the current ACOG/SFTM definition of first stage arrest, which is only applicable when dilation ≥ 6cm. They found that the adaptive model was better able to discriminate CD-related outcomes, hemorrhage, and neonatal depression.

Strengths of the study included prospectively collected data. Weaknesses included retrospective design and limited generalizability to women who have previously had a CD. Prospective studies are needed to better evaluate the utility of multifactorial models in clinical management of labor disorders.

Click to read the study in AJOG

Relevant Reading: Contemporary Patterns of Spontaneous Labor With Normal Neonatal Outcomes

In-Depth [retrospective cohort]: This study compared a mathematical model in which expected dilation was predicted by uterine activity, dilation, station and effacement at the previous exam and epidural anesthesia, with conventional definitions of first stage arrest among 4703 singleton deliveries to women who had never had a CD. Outcomes of interest were CD secondary to first stage labor disorder, CD secondary to fetal heart rate, obstetrical hemorrhage and neonatal depression as determined by area under the curve (AUC).


For the CD outcomes, AUC for duration of arrest when dilation ≥6cm was 0.55-0.65 (p < 0.01) using this adaptive multifactorial model. The AUC for dilation percentile was 0.81-0.93 (p < 0.01) and for station percentile was 0.78-0.82 (p < 0.01). Only station percentile was significantly discriminative for hemorrhage and neonatal depression, with AUC 0.58-0.61 (p < 0.01).

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