{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,26]],"date-time":"2026-10-26T21:09:11Z","timestamp":1793048951867,"version":"4.5.0"},"reference-count":30,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2016,12,9]],"date-time":"2016-12-09T00:00:00Z","timestamp":1481241600000},"content-version":"vor","delay-in-days":8,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"Bill & Melinda Gates Foundation to the University of Oxford"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ultrasound in Obstet &amp; Gyne"],"published-print":{"date-parts":[[2016,12]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>Accurate gestational\u2010age (GA) estimation, preferably by ultrasound measurement of fetal crown\u2013rump length before 14 weeks' gestation, is an important component of high\u2010quality antenatal care. The objective of this study was to determine how GA can best be estimated by fetal ultrasound for women who present for the first time late in pregnancy with uncertain or unknown menstrual dates.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>INTERGROWTH\u201021<jats:sup>st<\/jats:sup> was a large, prospective, multicenter, population\u2010based project performed in eight geographically defined urban populations. One of its principal components, the Fetal Growth Longitudinal Study, aimed to develop international fetal growth standards. Each participant had their certain menstrual dates confirmed by first\u2010trimester ultrasound examination. Fetal head circumference (HC), biparietal diameter (BPD), occipitofrontal diameter (OFD), abdominal circumference (AC) and femur length (FL) were measured every 5 weeks from 14 weeks' gestation until delivery. For each participant, a single, randomly selected ultrasound examination was used to explore all candidate biometric variables and permutations to build models to predict GA. Regression equations were ranked based upon minimization of the mean prediction error, goodness of fit and model complexity. An automated machine learning algorithm, the Genetic Algorithm, was adapted to evaluate &gt; 64 000 potential polynomial equations as predictors.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Of the 4607 eligible women, 4321 (94%) had a pregnancy without major complications and delivered a live singleton without congenital malformations. After other exclusions (missing measurements in GA window and outliers), the final sample comprised 4229 women. Two skeletal measures, HC and FL, produced the best GA prediction, given by the equation log<jats:sub>e<\/jats:sub>(GA) = 0.03243 \u00d7 (log<jats:sub>e<\/jats:sub>(HC))<jats:sup>2<\/jats:sup> + 0.001644 \u00d7 FL \u00d7 log<jats:sub>e<\/jats:sub>(HC) + 3.813. When FL was not available, the best equation based on HC alone was log<jats:sub>e<\/jats:sub>(GA) = 0.05970 \u00d7 (log<jats:sub>e<\/jats:sub>(HC))<jats:sup>2<\/jats:sup> + 0.000000006409 \u00d7 (HC)<jats:sup>3<\/jats:sup> + 3.3258. The estimated uncertainty of GA prediction (half width 95% interval) was 6\u20137 days at 14 weeks' gestation, 12\u201314 days at 26 weeks' gestation and &gt; 14 days in the third trimester. The addition of FL to the HC model led to improved prediction intervals compared with using HC alone, but no further improvement in prediction was afforded by adding AC, BPD or OFD. Equations that included other measurements (BPD, OFD and AC) did not perform better.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Among women initiating antenatal care late in pregnancy, a single set of ultrasound measurements combining HC and FL in the second trimester can be used to estimate GA with reasonable accuracy. We recommend this tool for underserved populations but considerable efforts should be implemented to improve early initiation of antenatal care worldwide. \u00a9 2016 Authors. Ultrasound in Obstetrics &amp; Gynecology 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.15894","type":"journal-article","created":{"date-parts":[[2016,2,29]],"date-time":"2016-02-29T12:01:17Z","timestamp":1456747277000},"page":"719-726","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":153,"title":["Ultrasound\u2010based gestational\u2010age estimation in late pregnancy"],"prefix":"10.1002","volume":"48","author":[{"given":"A. T.","family":"Papageorghiou","sequence":"first","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B.","family":"Kemp","sequence":"additional","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W.","family":"Stones","sequence":"additional","affiliation":[{"name":"Faculty of Health Sciences Aga Khan University  Nairobi Kenya"},{"name":"School of Medicine University of St Andrews  St Andrews Scotland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E. O.","family":"Ohuma","sequence":"additional","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"},{"name":"Centre for Statistics in Medicine, Botnar Research Centre University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S. H.","family":"Kennedy","sequence":"additional","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M.","family":"Purwar","sequence":"additional","affiliation":[{"name":"Nagpur INTERGROWTH\u201021<sup>st<\/sup> Research Centre Ketkar Hospital  Nagpur India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L. J.","family":"Salomon","sequence":"additional","affiliation":[{"name":"Maternit\u00e9 Necker\u2010Enfants Malades, AP\u2010HP Universit\u00e9 Paris Descartes  Paris France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D. G.","family":"Altman","sequence":"additional","affiliation":[{"name":"Center for Statistics in Medicine, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. A.","family":"Noble","sequence":"additional","affiliation":[{"name":"Department of Engineering Science University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E.","family":"Bertino","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Pediatriche e dell'Adolescenza, Cattedra di Neonatologia Universit\u00e0 degli Studi di Torino  Turin Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M. G.","family":"Gravett","sequence":"additional","affiliation":[{"name":"Global Alliance to Prevent Prematurity and Stillbirth (GAPPS)  Seattle WA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R.","family":"Pang","sequence":"additional","affiliation":[{"name":"School of Public Health Peking University  Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L.","family":"Cheikh Ismail","sequence":"additional","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"F. C.","family":"Barros","sequence":"additional","affiliation":[{"name":"Programa de P\u00f3s\u2010Gradua\u00e7\u00e3o em Sa\u00fade e Comportamento Universidade Cat\u00f3lica de Pelotas  Pelotas RS Brazil"},{"name":"Programa de P\u00f3s\u2010Gradua\u00e7\u00e3o em Epidemiologia Universidade Federal de Pelotas  Pelotas RS Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A.","family":"Lambert","sequence":"additional","affiliation":[{"name":"Nuffield Department of Obstetrics &amp; Gynaecology and Oxford Maternal &amp; Perinatal Health Institute, Green Templeton College University of Oxford  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Y. A.","family":"Jaffer","sequence":"additional","affiliation":[{"name":"Department of Family &amp; Community Health Ministry of Health  Muscat Sultanate of Oman"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C. 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