title: Preterm birth in the United States: current issues and future perspectives.
authors.forename: K R
authors.initials: KR
authors.lastname: Simpson
mesh_terms: D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000453:epidemiology / Q000517:prevention & control*; D011247:Pregnancy; D012307:Risk Factors; D014481:United States / Q000453:epidemiology