Association Between Active Phase of the Second Stage of Labour and Obstetrical Anal Sphincter Injury Risk: A Contemporary, Retrospective, Population-Based Cohort Study.

Jocelyn Stairs, Victoria M Allen, Amy Dodge, Aisling Clancy, Christy G Woolcott

Abstract read

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Article in International urogynecology journal, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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5 authors.

Jocelyn StairsDepartment of Obstetrics and Gynecology, Dalhousie University, 5850/5980 University Avenue, P.O. Box 9700, Halifax, NS, B3K 6R8, Canada. jocelyn.stairs@dal.ca.ORCID 0000-0002-6748-2310

Victoria M AllenDepartment of Obstetrics and Gynecology, Dalhousie University, 5850/5980 University Avenue, P.O. Box 9700, Halifax, NS, B3K 6R8, Canada.

Amy DodgeFaculty of Medicine, Dalhousie University, Halifax, Canada.

Aisling ClancyDepartment of Obstetrics and Gynecology, University of Ottawa, Ottawa, Canada.

Christy G WoolcottDepartment of Obstetrics and Gynecology, Dalhousie University, 5850/5980 University Avenue, P.O. Box 9700, Halifax, NS, B3K 6R8, Canada.

Funding

Research Nova Scotia 2022-2330

6 · The paper itself

Abstract

introduction and hypothesisAlthough the association between the prolonged second stage of labour and obstetrical anal sphincter injury (OASI) risk has been established, the contribution of the duration of the active phase (time spent pushing) remains unclear. This study was aimed at estimating the association between the duration of the active phase of the second stage of labour and OASI risk among nulliparous pregnant persons.

methodsWe conducted a population-based, retrospective cohort study of nulliparous pregnant persons who gave birth to a singleton, non-anomalous, vertex foetus at ≥ 37 weeks' gestational age from 2017 to 2021. Poisson regression models adjusting for confounders were developed to estimate the risk ratio (RR) with 95% confidence intervals (CI) for the association between duration of the active phase, and total duration of the second stage, of labour and OASI.

resultsOf 4963 persons, 471 (9.5%) cohort members sustained an OASI (8.7% third-degree and 0.8% fourth-degree). An active phase ≥ 120 min was associated with a 92% higher risk of OASI compared with 30 to < 60 min (RR 1.92, 95% CI 1.51-2.45). When stratified by mode of delivery, RRs estimated for this association were attenuated (spontaneous: 0.92, 95% CI 0.56-1.53; vacuum: 1.37, 95% CI 0.77-2.45; forceps: 0.85, 95% CI 0.63-1.15). When total duration of the second stage was considered, a duration ≥ 120 min was associated with a 59% increased risk of OASI compared with 30 to < 60 min (1.59, 95% CI 1.17-2.16).

conclusionIncreasing duration of the active phase of the second stage of labour is associated with an increased risk of OASI.

Indexed as

Anal CanalDelivery, ObstetricLabor Stage, SecondObstetric Labor ComplicationsAdultCohort StudiesFemaleHumansPregnancyRetrospective StudiesRisk FactorsTime FactorsActive second stage of labourNulliparasObstetrical anal sphincter injuryOperative vaginal delivery

Identifiers

PMID41427990

DOI10.1007/s00192-025-06360-2

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.