{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T21:20:32Z","timestamp":1783459232555,"version":"3.55.0"},"reference-count":20,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T00:00:00Z","timestamp":1779148800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T00:00:00Z","timestamp":1779148800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100000272","name":"National Institute for Health and Care Research","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000272","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Obstet Gynecol Scand"],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Little is known about the pelvic floor hiatal dimensions in labor, despite this being the soft tissue complex through which the fetus passes in a vaginal delivery. Intrapartum assessment of pelvic floor hiatal dimensions, particularly in the second stage of labor, may improve understanding of the variation in levator hiatal measurements and their change between maternal and fetal characteristics. Study design: To assess the levator hiatal dimensions at rest during the passive second stage of labor using three\u2010dimensional (3D) transperineal ultrasound, participants were consented prospectively, and ultrasound assessment was performed. The study population comprised nulliparous women at term (37\u201342 gestation) with a live singleton pregnancy.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Material and Methods<\/jats:title>\n                    <jats:p>Participants eligible for participation were recruited for the \u201cSONO\u2010BIRTH\u201d study. Transperineal ultrasound was performed in the second stage of labor. The 3D pelvic floor volumes were uploaded into software to measure the levator hiatal area, levator hiatal circumference, transverse hiatal diameter, and the anteroposterior hiatal distance. Maternal characteristics (age, body mass index, and ethnicity) were collected from antenatal booking forms. Other variables including gestational age and head\u2010perineum distance (HPD) were recorded at the time of the ultrasound assessment, as well as birthweight.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Of 186 participants consecutively recruited, 153 ultrasound volumes were measured. For the maternal characteristic of age, a significant association was observed with increasing maternal age and levator hiatal area (LHa) (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u2009=\u20090.26\u2009cm\n                      <jats:sup>2<\/jats:sup>\n                      , 95% CI 0.08; 0.43,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.004). Differences were also observed in ethnicity, with Asian and other non\u2010European ethnicities associated with a smaller LHa compared to White British (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u2009=\u2009\u22122.92\u2009cm\n                      <jats:sup>2<\/jats:sup>\n                      , 95% CI \u22125.20; \u22120.0.64,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.012) and (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u2009=\u2009\u22122.70\u2009cm\n                      <jats:sup>2<\/jats:sup>\n                      , 95% CI \u22125.29; \u22120.11,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.041), respectively. LHa decreased significantly and HPD increased (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u2009=\u2009\u22120.35\u2009cm\n                      <jats:sup>2<\/jats:sup>\n                      , 95% CI \u22120.45; \u22120.26,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). No association was found between hiatal dimensions and body mass index (BMI). In LHa measurements across gestations, a trend was observed toward a larger area with advancing gestational age, although the magnitude of the correlation was small (rho\u2009=\u20090.17,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.031).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>We report the relationship between\u00a0the levator muscle pelvic floor dimensions in the passive second stage of labor and maternal age, BMI, ethnicity, and gestational age. A higher fetal head station is associated with smaller pelvic floor dimensions as is non European ethnicity.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/aogs.70229","type":"journal-article","created":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T06:14:46Z","timestamp":1779257686000},"page":"1338-1343","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Association between maternal and fetal characteristics and levator hiatal dimensions in the second stage of labor"],"prefix":"10.1111","volume":"105","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9672-0237","authenticated-orcid":false,"given":"Mariya","family":"Kovalenko","sequence":"first","affiliation":[{"name":"Department of Digestion, Metabolism and Reproduction Imperial College London  London UK"},{"name":"Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giulia","family":"Zamagni","sequence":"additional","affiliation":[{"name":"Clinical Epidemiology and Public Health Research Unit Institute for Maternal and Child Health\u2013IRCCS \u201cBurlo Garofolo\u201d  Trieste Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-5603-2887","authenticated-orcid":false,"given":"Claudia","family":"Montero Carreras","sequence":"additional","affiliation":[{"name":"Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust  London UK"},{"name":"Department of Obstetrics, Gynecology, and Reproductive Medicine Institut Universitari Dexeus  Barcelona Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sana","family":"Usman","sequence":"additional","affiliation":[{"name":"Department of Digestion, Metabolism and Reproduction Imperial College London  London UK"},{"name":"Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arwa","family":"Hanidu","sequence":"additional","affiliation":[{"name":"Department of Digestion, Metabolism and Reproduction Imperial College London  London UK"},{"name":"Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust  London UK"},{"name":"Department of Radiological Sciences, College of Health and Rehabilitation Sciences Princess Nourah Bint Abdulrahman University  Riyadh Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tamara","family":"Stampalija","sequence":"additional","affiliation":[{"name":"Unit of Fetal Medicine and Prenatal Diagnosis Institute for Maternal and Child Health IRCCS \u201cBurlo Garofolo\u201d  Trieste Italy"},{"name":"Department of Medicine, Surgery and Health Sciences University of Trieste  Trieste Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lorenzo","family":"Monasta","sequence":"additional","affiliation":[{"name":"Clinical Epidemiology and Public Health Research Unit Institute for Maternal and Child Health\u2013IRCCS \u201cBurlo Garofolo\u201d  Trieste Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2104-5561","authenticated-orcid":false,"given":"Christoph","family":"Lees","sequence":"additional","affiliation":[{"name":"Department of Digestion, Metabolism and Reproduction Imperial College London  London UK"},{"name":"Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare NHS Trust  London UK"},{"name":"Department of Development &amp; Regeneration KU Leuven  Leuven Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,5,19]]},"reference":[{"key":"e_1_2_13_2_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.AOG.0000109207.22354.65"},{"key":"e_1_2_13_3_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0b013e3181a5ef23"},{"key":"e_1_2_13_4_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00192-004-1194-0"},{"key":"e_1_2_13_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.11214"},{"key":"e_1_2_13_6_1","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/15.11.2433"},{"key":"e_1_2_13_7_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.AOG.0000178779.62181.01"},{"key":"e_1_2_13_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.1072"},{"key":"e_1_2_13_9_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.3848"},{"key":"e_1_2_13_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.6313"},{"key":"e_1_2_13_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.19072"},{"key":"e_1_2_13_12_1","doi-asserted-by":"publisher","DOI":"10.1111\/aogs.13186"},{"key":"e_1_2_13_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2021.12.025"},{"key":"e_1_2_13_14_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.1899"},{"key":"e_1_2_13_15_1","doi-asserted-by":"publisher","DOI":"10.1111\/aogs.14620"},{"key":"e_1_2_13_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.19075"},{"key":"e_1_2_13_17_1","doi-asserted-by":"publisher","DOI":"10.1111\/aogs.13315"},{"key":"e_1_2_13_18_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2000.tb11669.x"},{"key":"e_1_2_13_19_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.3825"},{"key":"e_1_2_13_20_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.13456"},{"key":"e_1_2_13_21_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2007.02.041"}],"container-title":["Acta Obstetricia et Gynecologica Scandinavica"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/aogs.70229","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/full-xml\/10.1111\/aogs.70229","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/aogs.70229","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T21:02:07Z","timestamp":1783458127000},"score":1,"resource":{"primary":{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/10.1111\/aogs.70229"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,19]]},"references-count":20,"journal-issue":{"issue":"7","published-print":{"date-parts":[[2026,7]]}},"alternative-id":["10.1111\/aogs.70229"],"URL":"https:\/\/doi.org\/10.1111\/aogs.70229","archive":["Portico"],"relation":{},"ISSN":["0001-6349","1600-0412"],"issn-type":[{"value":"0001-6349","type":"print"},{"value":"1600-0412","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,19]]},"assertion":[{"value":"2026-01-05","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-04-05","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-05-19","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}