Objective: To compare the precision of biparietal diameter (BPD) and crown-rump length (CRL) as predictors of gestational age in the human fetus in the late first and early second trimesters, using a population-based approach.
Methods: We constructed term and gestational-age prediction curves for first-trimester dating, based on 11 041 pregnancies with 12 260 measurements of CRL and/or BPD from a population-based Norwegian clinical database. We used a population-based approach with local linear quantile regression, combined with a time-to-event strategy that compensates for induced births. Term prediction precision was assessed by estimating and comparing the prediction residual curves using a time-to-event analysis. Individual differences in gestational-age predictions from CRL and BPD were assessed using measurements performed on the same fetus on the same day. A sensitivity analysis was performed to evaluate the effect of not distinguishing between non-spontaneous and spontaneous births.
Results: CRL and BPD provided almost identical term prediction precision judged from the residual distribution. In about 51% of examinations, the difference in predicted gestational age was 1 day or less; 24% of examinations had a difference of 2 days, 14% had a difference of 3 days, 7% had a difference of 4 days and only 5% of all examinations had a difference of 5 days or more. Incorrectly removing induced births from the analysis, or treating them as spontaneous, would cause a substantial systematic prediction bias of about 2 days.
期刊介绍:
Ultrasound in Obstetrics & Gynecology (UOG) is the official journal of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) and is considered the foremost international peer-reviewed journal in the field. It publishes cutting-edge research that is highly relevant to clinical practice, which includes guidelines, expert commentaries, consensus statements, original articles, and systematic reviews. UOG is widely recognized and included in prominent abstract and indexing databases such as Index Medicus and Current Contents.