Document Detail

Correction of systematic bias in ultrasound dating in studies of small-for-gestational-age birth: an example from the Iowa Health in Pregnancy Study.
MedLine Citation:
PMID:  22886591     Owner:  NLM     Status:  MEDLINE    
The authors examined whether early ultrasound dating (≤20 weeks) of gestational age (GA) in small-for-gestational-age (SGA) fetuses may underestimate gestational duration and therefore the incidence of SGA birth. Within a population-based case-control study (May 2002-June 2005) of Iowa SGA births and preterm deliveries identified from birth records (n = 2,709), the authors illustrate a novel methodological approach with which to assess and correct for systematic underestimation of GA by early ultrasound in women with suspected SGA fetuses. After restricting the analysis to subjects with first-trimester prenatal care, a nonmissing date of the last menstrual period (LMP), and early ultrasound (n = 1,135), SGA subjects' ultrasound GA was 5.5 days less than their LMP GA, on average. Multivariable linear regression was conducted to determine the extent to which ultrasound GA predicted LMP dating and to correct for systematic misclassification that results after applying standard guidelines to adjudicate differences in these measures. In the unadjusted model, SGA subjects required a correction of +1.5 weeks to the ultrasound estimate. With adjustment for maternal age, smoking, and first-trimester vaginal bleeding, standard guidelines for adjudicating differences in ultrasound and LMP dating underestimated SGA birth by 12.9% and overestimated preterm delivery by 8.7%. This methodological approach can be applied by researchers using different study populations in similar research contexts.
Karisa K Harland; Audrey F Saftlas; Anne B Wallis; Jerome Yankowitz; Elizabeth W Triche; M Bridget Zimmerman
Publication Detail:
Type:  Evaluation Studies; Journal Article; Research Support, N.I.H., Extramural     Date:  2012-08-10
Journal Detail:
Title:  American journal of epidemiology     Volume:  176     ISSN:  1476-6256     ISO Abbreviation:  Am. J. Epidemiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-08-29     Completed Date:  2012-10-29     Revised Date:  2013-09-03    
Medline Journal Info:
Nlm Unique ID:  7910653     Medline TA:  Am J Epidemiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  443-55     Citation Subset:  IM    
Injury Prevention Research Center and Department of Epidemiology, University of Iowa, Iowa City, IA 52242-5000, USA.
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MeSH Terms
Bias (Epidemiology)*
Case-Control Studies
Data Interpretation, Statistical
Gestational Age*
Infant, Newborn
Infant, Small for Gestational Age*
Linear Models
Multivariate Analysis
Ultrasonography, Prenatal*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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