title: Indicators of cocaine exposure and preterm birth.
abstract: OBJECTIVE
  To identify predictors of cocaine exposure during pregnancy, using hair and urine assays and self-report, and the association with preterm birth.
  
  
  METHODS
  A nested case-control study was conducted in a cohort of 2611 black and white women enrolled in prenatal care in central North Carolina. Cocaine exposure was ascertained by self-report (263 cases, 612 controls), urine assays at 24-29 weeks' gestation (226 cases, 564 controls) and postpartum (160 cases, 408 controls), and postpartum hair assays (169 cases, 435 controls). The major metabolite of cocaine, benzoylecgonine, was measured in urine. Cocaine and benzoylecgonine were measured in hair.
  
  
  RESULTS
  Cocaine exposure was identified in 2% based on self-report, 5-6% based on urine assays, and 13-15% based on hair assays. Black ethnicity, lower education, and poverty were strongly predictive of positive hair assays. Hair cocaine and benzoylecgonine were not associated with preterm birth, with the possible exception of higher levels of cocaine and benzoylecgonine and birth before 34 weeks' completed gestation. The urine screen at 24-29 weeks' gestation also gave some indication of a possible association (odds ratio 1.7, 95% confidence interval 0.9, 3.5).
  
  
  CONCLUSIONS
  The study corroborates the incompleteness of cocaine exposure assessment by self-report and urine screens relative to hair assays. The strong demographic predictors of exposure suggest where intervention efforts should be targeted. The most sensitive markers of exposure, hair cocaine and benzoylecgonine, are not associated with preterm birth, perhaps because they reflect different patterns of cocaine exposure than the other measures.
authors.affiliation: Carolina Population Center, School of Public Health, University of North Carolina, Chapel Hill, North Carolina 27599-7400, USA. david_savitz@unc.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Laura
authors.initials: L
authors.lastname: Henderson
authors.forename: Nancy
authors.initials: N
authors.lastname: Dole
authors.forename: Amy
authors.initials: A
authors.lastname: Herring
authors.forename: Diana G
authors.initials: DG
authors.lastname: Wilkins
authors.forename: Douglas
authors.initials: D
authors.lastname: Rollins
authors.forename: John M
authors.initials: JM
authors.lastname: Thorp
mesh_terms: D016022:Case-Control Studies; D003042:Cocaine / Q000031:analogs & derivatives* / Q000032:analysis / Q000652:urine; D019970:Cocaine-Related Disorders / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006197:Hair / Q000737:chemistry; D006801:Humans; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012959:Socioeconomic Factors
chemical_list: C005618:benzoylecgonine; D003042:Cocaine