title: Comparison of gestational age classifications: date of last menstrual period vs. clinical estimate.
abstract: OBJECTIVE
  The purpose was to compare the two different measures of gestational age currently used on birth certificates (the duration of pregnancy based on the date of last menstrual period [LMP] and the clinical estimate [CE] as related to health status indicators. We contrasted these measures by race/ethnicity.
  
  
  METHODS
  NCHS natality files for 2000-2002 were used, selecting cases of single live birth to U.S. resident mothers with both LMP and CE gestational age information.
  
  
  RESULTS
  Approximately 75% of the records had valid LMP and CE values and for approximately one-half of these, the LMP and CE values did not exactly agree. Overall and for each race and ethnic group, the LMP measures resulted in higher proportions of very preterm, preterm, postterm and SGA births. CE value provided preterm rates of 7.9% and for LMP, 9.9%. The odds ratio of preterm birth for African-Americans using the CE measure was 1.78 [95% Cl 1.77-1.79]. The odds ratio using LMP was 1.93 [95% Cl 1.92-1.94]. Whites were the referent population.
  
  
  CONCLUSIONS
  Different measures of gestational age result in different overall and race-specific rates of very preterm, preterm, postterm, and SGA births. These findings indicate that substituting or combining these measures may have consequences.
authors: University of Alabama at Birmingham 35294-0022, USA.
authors: Martha S
authors: MS
authors: Wingate
authors: Greg R
authors: GR
authors: Alexander
authors: Pierre
authors: P
authors: Buekens
authors: Anjel
authors: A
authors: Vahratian
mesh_terms: D001741:Black or African American; D000367:Age Factors; D005260:Female; D005865:Gestational Age; D006305:Health Status Indicators; D006630:Hispanic or Latino; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008598:Menstruation / Q000208:ethnology / Q000502:physiology*; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000208:ethnology; D047928:Premature Birth / Q000208:ethnology; D012680:Sensitivity and Specificity; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D044465:White People