{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T06:54:14Z","timestamp":1791269654835,"version":"4.1.0"},"reference-count":53,"publisher":"Wiley","issue":"s2","license":[{"start":{"date-parts":[[2007,8,30]],"date-time":"2007-08-30T00:00:00Z","timestamp":1188432000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Paediatric Perinatal Epid"],"published-print":{"date-parts":[[2007,9]]},"abstract":"<jats:title>Summary<\/jats:title><jats:p>There are three primary methods of gestational age estimation: dating based on last menstrual period (LMP), ultrasound\u2010based dating and neonatal estimates. We review the strengths and limitations of each method as well as their implications for research. Dating based on LMP is a simple, low\u2010cost method of estimating gestational age. Limitations associated with the use of menstrual\u2010based dating include reporting problems such as uncertainty regarding the LMP date, possibly due to bleeding not associated with menses, as well as concerns about the incidence of delayed ovulation, which can result in invalid estimates of gestation, even for women with certain LMP dates. Given that most women in the US have at least one ultrasound during pregnancy, it is becoming increasingly common for clinicians to verify menstrual dates using early ultrasound. To calculate gestational age with the use of ultrasound, fetal measurements are compared with a gestational age\u2010specific reference. The primary limitation of this method is the fact that the gestational age estimates of symmetrically large or small fetuses will be biased. Further, given that ultrasound references were developed using pregnancies that were dated according to reliable LMP dates, they are potentially biased in the same direction as dates calculated according to LMP. Neonatal estimates of gestational age have been shown to be the least precise dating method. To highlight the research implications of the choice of a gestational dating method, we used data from the Routine Antenatal Diagnostic Imaging with Ultrasound Study to identify risk factors for post\u2010term delivery. Risk factors for post\u2010term delivery are shown to vary according to the choice of a gestational dating method, suggesting that some findings are an artefact of the choice of a method rather than evidence of causality.<\/jats:p>","DOI":"10.1111\/j.1365-3016.2007.00865.x","type":"journal-article","created":{"date-parts":[[2007,9,4]],"date-time":"2007-09-04T04:31:24Z","timestamp":1188880284000},"page":"86-96","source":"Crossref","is-referenced-by-count":229,"title":["The research implications of the selection of a gestational age estimation method"],"prefix":"10.1111","volume":"21","author":[{"given":"Courtney D.","family":"Lynch","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2007,8,30]]},"reference":[{"key":"e_1_2_9_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/0140-6736(91)91653-C"},{"key":"e_1_2_9_3_2","doi-asserted-by":"publisher","DOI":"10.2307\/2991522"},{"key":"e_1_2_9_4_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.1985.tb01347.x"},{"key":"e_1_2_9_5_2","doi-asserted-by":"publisher","DOI":"10.1136\/jech.38.1.79"},{"key":"e_1_2_9_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9378(74)90152-5"},{"key":"e_1_2_9_7_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-3016.2000.00275.x"},{"key":"e_1_2_9_8_2","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9378(80)90133-7"},{"key":"e_1_2_9_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9378(72)90525-X"},{"key":"e_1_2_9_10_2","doi-asserted-by":"publisher","DOI":"10.1093\/oxfordjournals.aje.a115930"},{"key":"e_1_2_9_11_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.earlhumdev.2005.06.004"},{"key":"e_1_2_9_12_2","doi-asserted-by":"publisher","DOI":"10.1097\/00001648-199509000-00015"},{"key":"e_1_2_9_13_2","doi-asserted-by":"publisher","DOI":"10.3109\/00016349009028681"},{"key":"e_1_2_9_14_2","doi-asserted-by":"publisher","DOI":"10.2307\/2532929"},{"key":"e_1_2_9_15_2","doi-asserted-by":"publisher","DOI":"10.2307\/2530453"},{"key":"e_1_2_9_16_2","doi-asserted-by":"publisher","DOI":"10.1002\/sim.716"},{"key":"e_1_2_9_17_2","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/13.2.394"},{"key":"e_1_2_9_18_2","doi-asserted-by":"publisher","DOI":"10.2105\/AJPH.89.2.213"},{"key":"e_1_2_9_19_2","doi-asserted-by":"publisher","DOI":"10.1097\/00001648-199509000-00012"},{"key":"e_1_2_9_20_2","first-page":"617","article-title":"Ultrasound and the prenatal diagnosis of congenital anomalies: a medicolegal perspective","volume":"74","author":"Horger EO","year":"1989","journal-title":"Obstetrics and Gynecology"},{"key":"e_1_2_9_21_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM199309163291201"},{"key":"e_1_2_9_22_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(84)90492-6"},{"key":"e_1_2_9_23_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(88)90636-8"},{"key":"e_1_2_9_24_2","first-page":"189","article-title":"A randomized trial of routine prenatal ultrasound","volume":"76","author":"Ewigman B","year":"1990","journal-title":"Obstetrics and Gynecology"},{"key":"e_1_2_9_25_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.1996.tb09796.x"},{"key":"e_1_2_9_26_2","first-page":"639","article-title":"American College of Obstetrics and Gynecology Practice Bulletin. 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