Duration of labor by gestational week in nulliparous women

Objectives: To assess whether labor length differs by week of gestation. Methods: In this observational cross-sectional study, we compared duration of labor by gestational age (36 + 0 through 40 + 6 weeks) in primiparous singleton parturients with vertex presentation. Data were acquired for a period of 24 months (2010-2011). Results: In general, the rate of change in cervical dilatation decreased as gestational week at delivery advanced: 1.8 ± 1.0 cm/h, 1.5 ± 0.9 cm/h, 1.3 ± 0.8 cm/h, 1.6 ± 1.5, and 1.3 ± 1.0 cm/h at 36th, 37th, 38th, 39th and 40th gestational week, respectively (p = 0.040). Concurrently, the total labor duration (1st + 2nd + 3rd stages) increased as gestational age advanced: 423.6 ± 180.9 min, 496.5 ± 212.6 min, 545.9 ± 247.1 min, 483.8 ± 256.3 min, and 568.2 ± 273.8 min at 36th, 37th, 38th, 39th and 40th gestational week, respectively (p = 0.013). Conclusions: Gestational week of pregnancy may alter the duration of labor, specifically, the length of labor increases as gestational week at delivery advances.