{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T10:04:12Z","timestamp":1777629852495,"version":"3.51.4"},"reference-count":29,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2025,4,3]],"date-time":"2025-04-03T00:00:00Z","timestamp":1743638400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003123","name":"Fetal Medicine Foundation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100003123","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ultrasound in Obstet &amp; Gyne"],"published-print":{"date-parts":[[2025,5]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To evaluate the accuracy of fetal biparietal diameter (BPD) measurement in comparison with crown\u2013rump length (CRL) measurement for pregnancy dating at 11\u201313\u2009weeks' gestation.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This was a retrospective multicenter cohort study performed in five maternity units in Spain, the UK, Belgium and Bulgaria between January 2011 and December 2019. We included all women who attended a routine ultrasound examination at 11\u2009+\u20090 to 13\u2009+\u20096\u2009weeks who had a singleton pregnancy with a viable non\u2010malformed fetus\/neonate and ultrasound\u2010derived measurements for both CRL and BPD, along with a comprehensive record of pregnancy outcomes. We developed a formula for pregnancy dating based on BPD using data from pregnancies conceived via <jats:italic>in\u2010vitro<\/jats:italic> fertilization (IVF) by applying a simple linear regression. We validated this formula both internally and externally and compared it with the most commonly used formulae (Robinson's CRL\u2010based and Kustermann's BPD\u2010based formulae) through utilization of the Euclidean distance, relative absolute error and mean squared error. We also examined the rate of induction of labor for post\u2010term pregnancy based on dating using each of the formulae.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>A total of 49\u2009492 women were included in the study, comprising 47\u2009223 (95.4%) who conceived spontaneously and 2269 (4.6%) who conceived via IVF. In the internal validation performed using data from IVF pregnancies, our newly developed formula showed no significant difference when compared with the true gestational age calculated using conception date, with a mean difference of 0.0006 (95%\u2009CI, \u20130.09 to 0.09)\u2009days. In contrast, the mean difference of Kustermann's BPD\u2010based formula was \u22120.31 (95%\u2009CI, \u22120.46 to \u22120.17)\u2009days and the mean difference of Robinson's CRL\u2010based formula was \u20131.78 (95%\u2009CI, \u20131.88 to \u20131.68)\u2009days. In the external validation using data from spontaneously conceived pregnancies, with dating using Robinson's formula as the reference for \u2018true\u2019 gestational age, both our formula and Kustermann's formula resulted in underestimation of gestational age, with significant mean differences of \u20131.25 (95%\u2009CI, \u20131.28 to \u20131.22)\u2009days and \u20130.96 (95%\u2009CI, \u20130.98 to \u20130.93)\u2009days, respectively. The largest differences compared with Robinson's formula\u2010based dating results were observed between 11\u2009+\u20090 and 12\u2009+\u20090\u2009weeks. Dating the pregnancy using Robinson's formula led to 8.1% of pregnancies identified as requiring induction after 41\u2009+\u20093\u2009weeks, compared with 6.8% (<jats:italic>P<\/jats:italic>\u2009&lt;\u20090.001) and 7.0% (<jats:italic>P<\/jats:italic>\u2009&lt;\u20090.001) when applying our formula and Kustermann's formula, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Pregnancy dating based on ultrasound measurement of fetal BPD between 11\u2009+\u20090 and 13\u2009+\u20096\u2009weeks' gestation is a reliable alternative to dating based on fetal CRL. \u00a9 2025 The Author(s). <jats:italic>Ultrasound in Obstetrics &amp; Gynecology<\/jats:italic> published by John Wiley &amp; Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.<\/jats:p><\/jats:sec>","DOI":"10.1002\/uog.29216","type":"journal-article","created":{"date-parts":[[2025,4,5]],"date-time":"2025-04-05T01:34:44Z","timestamp":1743816884000},"page":"560-566","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Biparietal diameter for first\u2010trimester pregnancy dating: multicenter cohort study"],"prefix":"10.1002","volume":"65","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0117-6388","authenticated-orcid":false,"given":"C.","family":"de Paco Matallana","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology Hospital Cl\u00ednico Universitario \u2018Virgen de la Arrixaca\u2019, El Palmar, Murcia, Spain; Institute for Biomedical Research of Murcia, IMIB\u2010Arrixaca, El Palmar  Murcia Spain"},{"name":"Faculty of Medicine Universidad de Murcia  Murcia Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1793-7049","authenticated-orcid":false,"given":"V.","family":"Rolle","sequence":"additional","affiliation":[{"name":"Statistics and Data Management Unit, iMaterna Foundation, Alcal\u00e1 de Henares  Madrid Spain"},{"name":"Biostatistics and Epidemiology Platform, Fundaci\u00f3n para la Investigaci\u00f3n y la Innovaci\u00f3n Biosanitaria del Principado de Asturias (FINBA), Asturias  Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A. M.","family":"Fidalgo","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Hospital Universitario de Torrej\u00f3n, Torrej\u00f3n de Ardoz  Madrid Spain"},{"name":"Faculty of Medicine Universidad Francisco de Vitoria, Pozuelo de Alarc\u00f3n  Madrid Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4253-3556","authenticated-orcid":false,"given":"J.","family":"S\u00e1nchez\u2010Romero","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Hospital Cl\u00ednico Universitario \u2018Virgen de la Arrixaca\u2019, El Palmar, Murcia, Spain; Institute for Biomedical Research of Murcia, IMIB\u2010Arrixaca, El Palmar  Murcia Spain"},{"name":"Faculty of Medicine Universidad de Murcia  Murcia Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2252-342X","authenticated-orcid":false,"given":"J. C.","family":"Jani","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology University Hospital Brugmann and Universit\u00e9 Libre de Bruxelles  Brussels Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8041-2181","authenticated-orcid":false,"given":"P.","family":"Chaveeva","sequence":"additional","affiliation":[{"name":"Fetal Medicine Unit, Shterev Hospital, Sofia and Medical University  Pleven Bulgaria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1687-0222","authenticated-orcid":false,"given":"J. L.","family":"Delgado","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Hospital Cl\u00ednico Universitario \u2018Virgen de la Arrixaca\u2019, El Palmar, Murcia, Spain; Institute for Biomedical Research of Murcia, IMIB\u2010Arrixaca, El Palmar  Murcia Spain"},{"name":"Faculty of Medicine Universidad de Murcia  Murcia Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1817-3092","authenticated-orcid":false,"given":"B.","family":"Santacruz","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Hospital Universitario de Torrej\u00f3n, Torrej\u00f3n de Ardoz  Madrid Spain"},{"name":"Faculty of Medicine Universidad Francisco de Vitoria, Pozuelo de Alarc\u00f3n  Madrid Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1266-0711","authenticated-orcid":false,"given":"K. 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