title: The impact of prenatal care on preterm births among twin gestations in the United States, 1989-2000.
abstract: OBJECTIVE
  The purpose of this study was to determine the association between prenatal care and preterm births among twin gestations in the presence and absence of high-risk pregnancy conditions.
  
  
  METHODS
  Twin birth data in the United States were used to determine the association between preterm birth and prenatal care with the use of logistic regression.
  
  
  RESULTS
  Of the 779,387 twin births, 54.7% twin births were delivered preterm. The rate was higher among black women than among white women in the presence (57.0% vs 51.2%, respectively) and absence (70.3% vs 61.6%, respectively) of prenatal care. The absence of prenatal care increased the relative risk for preterm birth by 1.24-fold among black women and by 1.22-fold among white women. Lack of prenatal care was associated with increased preterm birth rates in the presence of most high-risk conditions.
  
  
  CONCLUSIONS
  Prenatal care is associated with fewer twin preterm births in the presence and absence of high-risk conditions. Increased prenatal care participation may help decrease preterm birth rates and also narrow the black-white twin preterm birth disparity.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School/Robert Wood Johnson University Hospital, New Brunswick, NJ, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Vintzileos
authors.forename: Cande V
authors.initials: CV
authors.lastname: Ananth
authors.forename: John C
authors.initials: JC
authors.lastname: Smulian
authors.forename: William E
authors.initials: WE
authors.lastname: Scorza
mesh_terms: D044383:Black People; D004200:Diseases in Twins / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature / Q000453:epidemiology*; D011247:Pregnancy; D011295:Prenatal Care / Q000706:statistics & numerical data*; D012306:Risk; D014427:Twins; D014481:United States / Q000453:epidemiology; D044465:White People; D001741:Black or African American