TY - JOUR
T1 - Dating of pregnancy in first versus second trimester in relation to post-term birth rate
T2 - A cohort study
AU - Thagaard, Ida Näslund
AU - Krebs, Lone
AU - Lausten-Thomsen, Ulrik
AU - Larsen, Severin Olesen
AU - Holm, Jens Christian
AU - Christiansen, Michael
AU - Larsen, Torben
N1 - Publisher Copyright:
© 2016 Näslund Thagaard et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Objectives: To evaluate in a national standardised setting whether the performance of ultrasound dating during the first rather than the second trimester of pregnancy had consequences regarding the definition of pre- and post-term birth rates. Methods: A cohort study of 8,551 singleton pregnancies with spontaneous delivery was performed from 2006 to 2012 at Copenhagen University Hospital, Holbæk, Denmark. We determined the duration of pregnancy calculated by last menstrual period, crown rump length (CRL), biparietal diameter (1st trimester), BPD (2nd trimester), and head circumference and compared mean and median durations, the mean differences, the systematic discrepancies, and the percentages of pre-term and post-term pregnancies in relation to each method. The primary outcomes were post-term and pre-term birth rates defined by different dating methods. Results: The change from use of second to first trimester measurements for dating was associated with a significant increase in the rate of post-term deliveries from 2.1-2.9% and a significant decrease in the rate of pre-term deliveries from 5.4-4.6% caused by systematic discrepancies. Thereby 25.1%would pass 41 weeks when GA is defined by CRL and 17.3% when BPD (2nd trimester) is used. Calibration for these discrepancies resulted in a lower postterm birth rate, from 3.1-1.4%, when first compared to second trimester dating was used. Conclusions: Systematic discrepancies were identified when biometric formulas were used to determine duration of pregnancy. This should be corrected in clinical practice to avoid an overestimation of post-term birth and unnecessary inductions when first trimester formulas are used.
AB - Objectives: To evaluate in a national standardised setting whether the performance of ultrasound dating during the first rather than the second trimester of pregnancy had consequences regarding the definition of pre- and post-term birth rates. Methods: A cohort study of 8,551 singleton pregnancies with spontaneous delivery was performed from 2006 to 2012 at Copenhagen University Hospital, Holbæk, Denmark. We determined the duration of pregnancy calculated by last menstrual period, crown rump length (CRL), biparietal diameter (1st trimester), BPD (2nd trimester), and head circumference and compared mean and median durations, the mean differences, the systematic discrepancies, and the percentages of pre-term and post-term pregnancies in relation to each method. The primary outcomes were post-term and pre-term birth rates defined by different dating methods. Results: The change from use of second to first trimester measurements for dating was associated with a significant increase in the rate of post-term deliveries from 2.1-2.9% and a significant decrease in the rate of pre-term deliveries from 5.4-4.6% caused by systematic discrepancies. Thereby 25.1%would pass 41 weeks when GA is defined by CRL and 17.3% when BPD (2nd trimester) is used. Calibration for these discrepancies resulted in a lower postterm birth rate, from 3.1-1.4%, when first compared to second trimester dating was used. Conclusions: Systematic discrepancies were identified when biometric formulas were used to determine duration of pregnancy. This should be corrected in clinical practice to avoid an overestimation of post-term birth and unnecessary inductions when first trimester formulas are used.
UR - http://www.scopus.com/inward/record.url?scp=84955304798&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0147109
DO - 10.1371/journal.pone.0147109
M3 - Journal article
C2 - 26760299
AN - SCOPUS:84955304798
SN - 1932-6203
VL - 11
JO - PLoS One
JF - PLoS One
IS - 1
M1 - 0147109
ER -