Document Detail

Reducing misclassification in assignment of timing of events during pregnancy.
MedLine Citation:
PMID:  15613955     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Perinatal epidemiology studies often collect only the calendar month in which an event occurs in early pregnancy because it is difficult for women to recall a specific day when queried later in pregnancy or postpartum. Lack of day information may result in incorrect assignment of completed gestational month because calendar months and pregnancy months are not aligned.
METHODS: To examine the direction and magnitude of misclassification, we compared 3 methods for assignment of completed gestational month: 1) calendar month difference, 2) conditional month difference, and 3) imputed month midpoint. We used data from the Pregnancy, Infection, and Nutrition Study for simulations.
RESULTS: Calendar month difference misclassified 54% of events as 1 month later in pregnancy compared with the actual completed month of gestation. Each of the other 2 methods misclassified approximately 12% of events to 1 month earlier and 12% to 1 month later.
CONCLUSIONS: Calendar month difference, a common method, has the greatest misclassification. Conditional month difference and imputed month midpoint, which require little effort to implement, are superior to calendar month difference for reducing misclassification.
Juan Yang; Katherine E Hartmann; Amy H Herring; David A Savitz
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Epidemiology (Cambridge, Mass.)     Volume:  16     ISSN:  1044-3983     ISO Abbreviation:  Epidemiology     Publication Date:  2005 Jan 
Date Detail:
Created Date:  2004-12-22     Completed Date:  2005-05-19     Revised Date:  2013-09-19    
Medline Journal Info:
Nlm Unique ID:  9009644     Medline TA:  Epidemiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  121-3     Citation Subset:  IM    
Departments of Epidemiology, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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MeSH Terms
Cohort Studies
Gestational Age
North Carolina
Postpartum Period
Prospective Studies
Surrogate Mothers*
Time Factors
Grant Support

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

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