title: Modeling community-level effects on preterm birth.
abstract: OBJECTIVE
  We demonstrate modeling of community-level socioeconomic influences on risk of preterm birth (< 37 weeks gestation) in the Pregnancy, Infection, and Nutrition (PIN) Study.
  
  
  METHODS
  Community-level information from the US Census was linked to 930 White and 817 African-American (Black) participants from a prospective cohort in central North Carolina through geocoded addresses, providing 123 census tracts with community-level and individual-level data for multi-level statistical analyses.
  
  
  RESULTS
  Preterm delivery was experienced by 12.1% of Black and 10.4% of White participants. No appreciable aggregation of risk by community was discernable for White women. For Black women, random-coefficient logistic regression tract-specific preterm prevalence estimates ranged from 10.1% to 14.5%, "shrunk" from observed prevalences of 0% to 100%. Adding tract-level variables to the model representing median splits for household income and percent of single women heads of households with dependents, adjusting for individual-level maternal age and household income, accounted for much of the remaining between-tracts variation.
  
  
  CONCLUSIONS
  Residing in a wealthier tract (> $30,000/year median income) was associated with reduced risk for Black women, adjusted OR = 0.59 (95% CI: 0.36, 0.96). The estimated conditional effect of lower community prevalence of female headed households was OR = 0.71 (95% CI: 0.43, 1.17).
authors.affiliation: Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, NC 27599, USA. Jay_Kaufman@unc.edu
authors.forename: Jay S
authors.initials: JS
authors.lastname: Kaufman
authors.forename: Nancy
authors.initials: N
authors.lastname: Dole
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D002648:Child; D015331:Cohort Studies; D019058:Community Networks; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D016015:Logistic Models; D007752:Obstetric Labor, Premature / Q000453:epidemiology* / Q000209:etiology; D017063:Outcome Assessment, Health Care; D011247:Pregnancy; D011446:Prospective Studies; D018570:Risk Assessment; D012959:Socioeconomic Factors; D044465:White People