{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T22:48:51Z","timestamp":1787870931530,"version":"build-2784847793"},"reference-count":42,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2024,7,24]],"date-time":"2024-07-24T00:00:00Z","timestamp":1721779200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Obstet Gynecol Scand"],"published-print":{"date-parts":[[2024,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Introduction<\/jats:title><jats:p>In clinical experience, occiput posterior (OP) position is associated with longer labor duration than occiput anterior (OA) position, but few studies have investigated the association between labor duration and fetal position. We aimed to compare duration of the active phase of labor in OP deliveries with OA deliveries in a contemporary population using survival methods. Secondary aims were to compare the frequencies of operative interventions, obstetric anal sphincter injuries (OASIS), postpartum hemorrhage, and newborn outcomes in OP with OA deliveries.<\/jats:p><\/jats:sec><jats:sec><jats:title>Material and Methods<\/jats:title><jats:p>We did a historical cohort study in three university hospitals in Norway from 2012 to 2022. Women with a single fetus in cephalic presentation, no previous cesarean section and gestational age \u226537\u2009weeks were eligible and stratified into the first four groups of the Robson ten\u2010group classification system (TGCS). We estimated the mean duration and calculated the hazard ratio (HR) for delivery using survival analyses. Cesarean sections and instrumental vaginal deliveries were censored.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The study population comprised 112\u2009019 women, 105\u2009571 (94.2%) were delivered in OA and 6448 (5.8%) in OP position. The estimated mean duration of the active phase of labor was longer in women with the fetus in OP position in all four TGCS groups. The estimated duration was longer in the OP groups in analyses stratified with respect to epidural analgesia and oxytocin augmentation. The graphical abstract illustrates the probability of delivery in OP compared with OA position in merged TGCS groups 1 and 2a, as a function of time. The unadjusted HR was 0.33 (95% CI 0.31\u20130.36) for fetuses delivered in OP position compared with OA position in TGCS group 1, 0.25 (95% CI 0.21\u20130.27) in group 2a, 0.70 (95% CI 0.67\u20130.73) in group 3, and 0.61 (95% CI 0.55\u20130.67) in group 4a, respectively. Neither maternal age, gestational age, BMI nor birthweight had confounding effect. Operative delivery rates and OASIS rates were higher in OP position in all four groups.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>We found longer duration of the active phase of labor in women with the fetus delivered in OP position in all four TGCS groups.<\/jats:p><\/jats:sec>","DOI":"10.1111\/aogs.14929","type":"journal-article","created":{"date-parts":[[2024,7,24]],"date-time":"2024-07-24T14:23:33Z","timestamp":1721831013000},"page":"1888-1897","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Associations between fetal position at delivery and duration of active phase of labor: A historical cohort study"],"prefix":"10.1111","volume":"103","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-6443-1376","authenticated-orcid":false,"given":"Birgitte","family":"Eide","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology Stavanger University Hospital  Stavanger Norway"},{"name":"Department of Clinical Science, Medical Faculty University of Bergen  Bergen Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5163-9512","authenticated-orcid":false,"given":"Ragnar Kvie","family":"Sande","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Stavanger University Hospital  Stavanger Norway"},{"name":"Department of Clinical Science, Medical Faculty University of Bergen  Bergen Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Phillip","family":"Von\u00a0Brandis","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Stavanger University Hospital  Stavanger Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2931-2668","authenticated-orcid":false,"given":"J\u00f8rg","family":"Kessler","sequence":"additional","affiliation":[{"name":"Department of Clinical Science, Medical Faculty University of Bergen  Bergen Norway"},{"name":"Department of Obstetrics and Gynecology Haukeland University Hospital  Bergen Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5225-0672","authenticated-orcid":false,"given":"Christian","family":"Tappert","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Trondheim University Hospital (St Olavs Hospital)  Trondheim Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3162-9595","authenticated-orcid":false,"given":"Torbj\u00f8rn Moe","family":"Eggeb\u00f8","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Stavanger University Hospital  Stavanger Norway"},{"name":"Department of Clinical and Molecular Medicine Norwegian University of Science and Technology  Trondheim Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2024,7,24]]},"reference":[{"key":"e_1_2_11_2_1","unstructured":"ArganiC SatinA BerghellaV BarberaA.UpToDate.2022. 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