{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T13:11:37Z","timestamp":1771333897332,"version":"3.50.1"},"reference-count":34,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2014,12,2]],"date-time":"2014-12-02T00:00:00Z","timestamp":1417478400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000071","name":"National Institute of Child Health and Human Development","doi-asserted-by":"publisher","award":["R24HD047879"],"award-info":[{"award-number":["R24HD047879"]}],"id":[{"id":"10.13039\/100000071","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000071","name":"National Institute of Child Health and Human Development","doi-asserted-by":"publisher","award":["F31HD079182"],"award-info":[{"award-number":["F31HD079182"]}],"id":[{"id":"10.13039\/100000071","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000071","name":"National Institute of Child Health and Human Development","doi-asserted-by":"publisher","award":["R24HD042849"],"award-info":[{"award-number":["R24HD042849"]}],"id":[{"id":"10.13039\/100000071","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Birth"],"published-print":{"date-parts":[[2015,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Duration of the second stage of labor has been suggested as an independent risk factor for clinically detectable obstetric anal sphincter injury in low\u2010risk nulliparous women.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A retrospective 5\u2010year cohort study was conducted in a <jats:styled-content style=\"fixed-case\">UK<\/jats:styled-content> obstetrics center which included a high\u2010risk delivery unit and a low\u2010risk birthing center. The study included 4,831 nulliparous women with vertex\u2010presenting, single, live\u2010born infants at term, stratified according to spontaneous or instrumental delivery. Binary logistic regression models were used to examine the association between duration of second stage and sphincter injury.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Three\u2010hundred twenty\u2010five of 4,831 women (6.7%) sustained sphincter injuries. In spontaneously delivering women, no association between duration of the second stage and the likelihood of sphincter injury was recorded. Factors associated with increased likelihood of sphincter injury included older maternal age, higher birthweight, and Southeast Asian ethnicity. In contrast, for women undergoing instrumental delivery, a longer second stage was associated with an increased sphincter injury risk of 6 percent per 15\u00a0minutes in the second stage of labor before delivery.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>For spontaneous vaginal deliveries, duration of the second stage of labor was not an independent risk factor for obstetric anal sphincter injury. The association between prolonged second stage and sphincter injury for instrumental deliveries is likely explained by the risk posed by the use of the instruments themselves or by delay in initiating instrumental assistance. Attempts to modify the duration of the second stage for prevention of sphincter injuries are unlikely to be beneficial and may be detrimental.<\/jats:p><\/jats:sec>","DOI":"10.1111\/birt.12137","type":"journal-article","created":{"date-parts":[[2014,12,2]],"date-time":"2014-12-02T07:12:32Z","timestamp":1417504352000},"page":"86-93","source":"Crossref","is-referenced-by-count":24,"title":["Influence of the Duration of the Second Stage of Labor on the Likelihood of Obstetric Anal Sphincter Injury"],"prefix":"10.1111","volume":"42","author":[{"given":"Catherine E.","family":"Aiken","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynaecology University of Cambridge Cambridge UK"},{"name":"NIHR Cambridge Comprehensive Biomedical Research Centre Cambridge UK"},{"name":"University of Cambridge Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit Institute of Metabolic Science Addenbrooke's Hospital Cambridge UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abigail R.","family":"Aiken","sequence":"additional","affiliation":[{"name":"Office of Population Research Princeton University Princeton NJ USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrew","family":"Prentice","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynaecology University of Cambridge Cambridge UK"},{"name":"NIHR Cambridge Comprehensive Biomedical Research Centre Cambridge UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2014,12,2]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0b013e31826ac4bb"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.gco.0000191901.69320.a0"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2004.02.064"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0b013e318169cdee"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1111\/jan.12005"},{"issue":"2","key":"e_1_2_8_7_1","doi-asserted-by":"crossref","first-page":"1516","DOI":"10.1111\/1471-0528.12363","article-title":"Third\u2010 and fourth\u2010degree perineal tears among primiparous women in England between 2000 and 2012: Time trends and risk factors","volume":"120","author":"Gurol\u2010Urganci I","year":"2013","journal-title":"BJOG"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.AOG.0000242616.56617.ff"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2004.12.007"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2009.03.028"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.0730-7659.2006.00088.x"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.3109\/14767058.2012.746308"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1523-536X.2006.00129.x"},{"key":"e_1_2_8_14_1","volume-title":"Greentop Guideline 62; 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