Progression of the first stage of spontaneous labour: A prospective cohort study in two sub-Saharan African countries

Abstract

BackgroundEscalation in the global rates of labour interventions, particularly cesarean section and oxytocin augmentation, has renewed interest in a better understanding of natural labour progression. Methodological advancements in statistical and computational techniques addressing the limitations of pioneer studies have led to novel findings and triggered a re-evaluation of current labour practices. As part of the World Health Organization's Better Outcomes in Labour Difficulty (BOLD) project, which aimed to develop a new labour monitoring-to-action tool, we examined the patterns of labour progression as depicted by cervical dilatation over time in a cohort of women in Nigeria and Uganda who gave birth vaginally following a spontaneous labour onset.Methods and findingsThis was a prospective, multicentre, cohort study of 5,606 women with singleton, vertex, term gestation who presented at ≤ 6 cm of cervical dilatation following a spontaneous labour onset that resulted in a vaginal birth with no adverse birth outcomes in 13 hospitals across Nigeria and Uganda. We independently applied survival analysis and multistate Markov models to estimate the duration of labour centimetre by centimetre until 10 cm and the cumulative duration of labour from the cervical dilatation at admission through 10 cm. Multistate Markov and nonlinear mixed models were separately used to construct average labour curves. All analyses were conducted according to three parity groups: parity = 0 (n = 2,166), parity = 1 (n = 1,488), and parity = 2+ (n = 1,952). We performed sensitivity analyses to assess the impact of oxytocin augmentation on labour progression by re-examining the progression patterns after excluding women with augmented labours. Labour was augmented with oxytocin in 40% of nulliparous and 28% of multiparous women. The median time to advance by 1 cm exceeded 1 hour until 5 cm was reached in both nulliparous and multiparous women. Based on a 95th percentile threshold, nulliparous women may take up to 7 hours to progress from 4 to 5 cm and over 3 hours to progress from 5 to 6 cm. Median cumulative duration of labour indicates that nulliparous women admitted at 4 cm, 5 cm, and 6 cm reached 10 cm within an expected time frame if the dilatation rate was ≥ 1 cm/hour, but their corresponding 95th percentiles show that labour could last up to 14, 11, and 9 hours, respectively. Substantial differences exist between actual plots of labour progression of individual women and the ‘average labour curves’ derived from study population-level data. Exclusion of women with augmented labours from the study population resulted in slightly faster labour progression patterns.ConclusionsCervical dilatation during labour in the slowest-yet-normal women can progress more slowly than the widely accepted benchmark of 1 cm/hour, irrespective of parity. Interventions to expedite labour to conform to a cervical dilatation threshold of 1 cm/hour may be inappropriate, especially when applied before 5 cm in nulliparous and multiparous women. Averaged labour c...

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“…Current labour practices have seen a rapid escalation in the application of interventions to initiate, accelerate, monitor, or terminate the physiological process of labour, all with the aim of improving birth outcomes. Recent studies suggest that the benchmark for assessing normal labour progression, which was derived from studies conducted over 60 years ago, may not be appropriate for clinical decision making for individual women 7, 8. Although unnecessary labour interventions are generally more common in middle‐ and high‐income settings,9 the routine use of ineffective and potentially harmful labour practices are also widespread in resource‐limited settings, with the consequent misallocation of scarce resources and a further widening of the equity gap 10, 11, 12.…”

“…Recent studies suggest that the benchmark for assessing normal labour progression, which was derived from studies conducted over 60 years ago, may not be appropriate for clinical decision making for individual women. 7,8 Although unnecessary labour interventions are generally more common in middle-and high-income settings, 9 the routine use of ineffective and potentially harmful labour practices are also widespread in resource-limited settings, with the consequent misallocation of scarce resources and a further widening of the equity gap. [10][11][12] On the other hand, failure to employ effective labour interventions when needed is also a recognised contributor to health inequities and poor quality of care during childbirth.…”

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“…Furthermore, the different obstetrical interventions that are more commonly used (inductions, epidural anesthesia and oxytocin use) may affect the labor process. Recent studies suggest that labor progression in contemporary labor cohorts differs from Friedman's results (30)(31)(32)(33). A longer duration of the active phase and a later transition from the latent to the active phase than previously described have been reported (30)(31)(32).…”

“…In a study on 62,415 nulli-and multiparous women with a term singleton pregnancy, spontaneous onset of labor and vaginal delivery, Zhang et al determined that labor progressed more slowly between 4-6 cm than previously described by Friedman and that the acceleration phase started at a cervical dilatation of 6 cm (30) ( Figure 5). Oladapo et al studied labor patterns of 5,606 nulli-and multiparous women in a sub-Saharan African population and found, similar to Zhang et al, greater individual variability in labor progression than generally appreciated and that the acceleration phase may not start until 5 cm cervical dilatation (33). …”

“…There appears to be a normal physiological variation in the duration of labor, particularly in early labor, which may not be linear from 3-4 cm of cervical dilatation according to recent studies on contemporary cohorts of women in labor (30,31,33). The effectiveness of uterine contractions and the duration of labor may be influenced by numerous factors such as parity, fetal position and size and pelvic size and shape, maternal psychological state and maternal obesity (25,45).…”