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BACKGROUND AND PROBLEM: During childbirth, one of the most common diagnoses of pathology is 'failure to progress', frequently resulting in labour augmentation and intervention cascades. However, failure to progress is poorly defined and evidence suggests that some instances of slowing, stalling and pausing labour patterns may represent physiological plateaus. AIM: To explore how midwives conceptualise physiological plateaus and the significance such plateaus may have for women's labour trajectory and birth outcome. METHODS: Twenty midwives across Australia participated in semi-structured interviews between September 2020 and February 2022. Constructivist grounded theory methodology was applied to analyse data, including multi-phasic coding and application of constant comparative methods, resulting in a novel theory of physiological plateaus that is firmly supported by participant data. FINDINGS: This study found that the conceptualisation of plateauing labour depends largely on health professionals' philosophical assumptions around childbirth. While the Medical Dominant Paradigm frames plateaus as invariably pathological, the Holistic Midwifery Paradigm acknowledges plateaus as a common and valuable element of labour that serves a self-regulatory purpose and results in good birth outcomes for mother and baby. DISCUSSION: Contemporary medicalised approaches in maternity care, which are based on an expectation of continuous labour progress, appear to carry a risk for a misinterpretation of physiological plateaus as pathological. CONCLUSION: This study challenges the widespread bio-medical conceptualisation of plateauing labour as failure to progress, encourages a renegotiation of what can be considered healthy and normal during childbirth, and provides a stimulus to acknowledge the significance of childbirth philosophy for maternity care practice.

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Background: Friedman's curve, despite acknowledged limitations, has greatly influenced labour management. Interventions to hasten birth are now ubiquitous, challenging the contemporary study of normal labour. Our primary purpose was to characterise normal active labour and pushing durations in a large, contemporary sample experiencing minimal intervention, stratified by parity, age, and body mass index (BMI). Methods: This is a secondary analysis of the national, validated Midwives Alliance of North America 4·0 (MANA Stats) data registry (n = 75,243), prospectively collected between Jan 1, 2012 and Dec 31, 2018 to describe labour and birth in home and birth center settings where common obstetric interventions [i.e., oxytocin, planned cesarean] are not available. The MANA Stats cohort includes pregnant people who intended birth in these settings and prospectively collects labour and birth processes and outcomes regardless of where birth or postpartum care ultimately occurs. Survival curves were calculated to estimate labour duration percentiles (e.g. 10th, 50th, 90th, and others of interest), by parity and sub-stratified by age and BMI. Findings: Compared to multiparous women (n = 32,882), nulliparous women (n = 15,331) had significantly longer active labour [e.g., median 7.5 vs. 3.3 h; 95th percentile 34.8 vs. 12.0 h] and significantly longer pushing phase [e.g., median 1.1 vs. 0.2 h; 95th percentile 5.5 vs. 1.1 h]. Among nulliparous women, maternal age >35 was associated with longer active first stage of labour and longer pushing phase, and BMI >30 kg/m² was associated with a longer active first stage of labour but a shorter pushing phase. Patterns among multiparous women were different, with those >35 years of age experiencing a slightly more rapid active labour and no difference in pushing duration, and those with BMI >30 kg/m² experiencing a slightly longer active labour but, similarly, no difference in pushing duration. Interpretation: Nulliparous women had significantly longer active first stage and pushing phase durations than multiparous women, with further variation noted by age and by BMI. Contemporary US women with low-risk pregnancies who intended birth in settings absent common obstetric interventions and in spontaneous labour with a live, vertex, term, singleton, non-anomalous fetus experienced labour durations that were often longer than prior characterizations, particularly among nulliparous women. Results overcome prior and current sampling limitations to refine understanding of normal labour durations and time thresholds signaling 'labour dystocia'. Funding: OHSU Nursing Innovation and OHSU University Shared Resources.

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Aim To measure the utility of the Simulation training model for training purposes over and above conventional methods of training for vaginal assessment during labour. Methods The study group included undergraduate trainees, and the control group included postgraduate trainees and qualified personnel, i.e. senior registrars and consultants. Participants from the study group were trained for vaginal assessment on the simulation training model. Then both the groups were tested on the model for accuracy in estimating each value of cervical dilatation and fetal station. Mean cervical dilatation and station accuracy scores were noted, and comparative analysis was done between the study and control groups. Results A total of 150 participants were included. The overall mean dilatation and station accuracy scores of a model trained study group participants were better than subjectively trained control group participants. Study group participants showed greater accuracy for smaller dilatations, i.e. 1, 2, 3, 4cm and middle dilatation, i.e. 5cm and 6cm (p value=<0.05). In contrast, comparing the two groups for higher dilatations from 6 to 10 cm did not show any statistical significance. Study group participants also showed greater accuracy for all the fetal stations except stations 0 and +1. Conclusions The simulation training model can be considered an in vitro training device to improve the trainees' understanding of cervical dilatation and fetal station and can be made a part of a routine obstetric teaching program.

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OBJECTIVE: To evaluate the discrepancy between historical and more recent descriptions of the first stage of labour by testing whether the statistical techniques used recently (repeated-measures polynomial and interval-censored regression) were appropriate for detection of periods of rapid acceleration of cervical dilatation as might occur at the time of transition from a latent to an active phase of labour. DESIGN AND SETTING: A simulation study using regression techniques. SAMPLE: We created a simulated data set for 500 000 labours with clearly defined latent and active phases using the parameters described by Friedman. Additionally, we created a data set comprising 500 000 labours with a progressively increasing rate of cervical dilatation. METHODS: Repeated-measures polynomial regression was used to create summary labour curves based on simulated cervical examinations. Interval-censored regression was used to create centimetre-by-centimetre estimates of rates of cervical dilatation and their 95th centiles. MAIN OUTCOME MEASURES: Labour summary curves and rates of cervical dilatation. RESULTS: Repeated-measures polynomial regression did not detect the rapid acceleration in cervical dilatation (i.e. acceleration phase) and overestimated lengths of labour, especially at smaller cervical dilatations. There was a two-fold overestimation in the mean rate of cervical dilatation from 4 to 6 cm. Interval-censored regression overestimated median transit times, at 4- to 5-cm cervical dilatation or when cervical examinations occurred less frequently than 0.5- to 1.5-hourly. CONCLUSION: Repeated-measures polynomial regression and interval-censored regression should not be routinely used to define labour progress because they do not accurately reflect the underlying data. TWEETABLE ABSTRACT: Repeated-measures polynomial and interval-censored regression techniques are not appropriate to model first stage of labour.

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