Advantages of the population-based approach to pregnancy dating demonstrated with results from 23 020 ultrasound examinations.
2012 (English)In: Ultrasound in Obstetrics and Gynecology, ISSN 0960-7692, E-ISSN 1469-0705, Vol. 39, no 5, 563-568 p.Article in journal (Refereed) Published
OBJECTIVE: To confirm the results from two previous evaluations of term prediction models in a third population, and to explore why biased predictions are unavoidable with sample-based models. METHODS: In a study population of 23 020 second-trimester ultrasound examinations, data were prospectively collected and registered over the period 1988-2009. Three different models for ultrasonically estimated date of delivery were applied to the measurements of fetal biparietal diameter (BPD) and femur length (FL), and the resulting term estimations were compared with the actual time of the delivery. The difference between the actual and the predicted date of delivery (the median bias) was calculated for each of the models, for three BPD/FL-measurement subgroups and for the study population as a whole. RESULTS: For the population-based model, the median bias was + 0.4 days for the BPD-based, and -0.4 days for the FL-based predictions, and the biases were stable over the inclusion ranges. The biases of the two traditional models varied with the size of the fetus at examination; median biases were -0.87 and + 2.2 days, respectively, with extremes -4.2 and + 4.8 days for the BPD-based, and + 1.72 days with range -0.8 to + 4.5 days for the FL-based predictions. The disagreement between these two methods was never less than 2 days. CONCLUSIONS: This study confirms the results from previous studies; median biases were negligible with term predictions from the population-based model, while those from the traditional models varied substantially. The biases, which have clinical implications, seem inevitable with the sample-based models, which, even when tentatively calibrated, will perform unsatisfactorily. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Place, publisher, year, edition, pages
2012. Vol. 39, no 5, 563-568 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-16219DOI: 10.1002/uog.10081PubMedID: 21898635OAI: oai:DiVA.org:ntnu-16219DiVA: diva2:515249
Used with permission from Copyright Clearance Center, John Wiley and Sons2012-04-122012-04-122012-06-29Bibliographically approved