Key result
Asian women had slower active labor (P<0.01) and reported less pain (P<0.001) compared to other ethnicities, while greater maternal weight and neuraxial analgesia also slowed labor.
Why the study?
Do patient characteristics (ethnicity, weight) affect the progress and pain of the first stage of nulliparous labor?
Observational (n=500)
Do patient characteristics (ethnicity, weight) affect the progress and pain of the first stage of nulliparous labor?
Mathematical modeling reveals that Asian ethnicity and greater maternal weight are associated with slower labor and slower onset of labor pain, though intersubject variability remains high.
Answers are grounded in this paper and cite their sources.
Ethnicity and weight associations with labor should not change practice; leaves open validation in prospective multi-ethnic cohorts.
Background: Patient characteristics may contribute to the progress and pain of labor. Quantitative evaluation of the effects of patient characteristics requires robust mathematical models of labor progress and labor pain. Methods: The authors retrospectively studied 100 sequential deliveries from each of five self-reported ethnic groups (Asian, Black, Hispanic, Other, and White). Demographic variables, cervical dilation, and numerical rating scores for pain before analgesia and cervical dilation were abstracted from the automated medical record. Labor progress was modeled with a biexponential function describing the latent and active phases of labor. Labor pain was modeled as a sigmoid function of cervical dilation by using a previously validated mathematical model. The covariates, including self-described ethnicity, were analyzed with NONMEM. Results: The biexponential function described the time course of labor progress better than several alternative functions, including the sigmoidal function introduced by Friedman. The sigmoidal function of labor pain described its dynamic nature well, with substantial intersubject variability. Asian women had slower active labor than other ethnicities (P < 0.01). Asian women also reported less pain during their labor compared to all other patients (P < 0.001). Slower labor progress was associated with less rapid progression of pain, but this did not obviate the effect of Asian ethnicity on pain. Neuraxial analgesia is strongly associated with slower labor (P < 0.0001). Greater maternal weight was associated with slower active labor (P < 0.0001). Conclusions: Mathematical models can be used to detect subtle effects of patient covariates on the progress and pain of the first stage of labor. Asian women and heavier women had slower labor and slower onset of labor pain than others. These effects were modest compared with the substantial remaining unexplained subject-to-subject variability in labor progress and labor pain.
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Debiec et al. (2010) conducted an observational in First stage of nulliparous labor (n=500). Asian ethnicity vs. Other ethnicities was evaluated on Labor progress (active phase) and labor pain (p=<0.01). Asian women had slower active labor (P<0.01) and reported less pain (P<0.001) compared to other ethnicities, while greater maternal weight and neuraxial analgesia also slowed labor.
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