US preterm births: "D" is for dismal.
Voelker
Rebecca
R
D002585:Cesarean Section / Q000706:statistics & numerical data; D005260:Female; D040361:Healthy People Programs; D006801:Humans; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology