Columbia subject headings:
Harvard subject headings:
Birth weight, Low--United States--Statistics.
Childbirth--Economic aspects--United States--Statistics.
Health surveys--United States--Statistics.
Pregnant women--Drug use--United States--Statistics.
Prenatal care--United States--Statistics.
United States--Statistics, Medical.
Princeton subject headings:
Birth weight, Low--United States--Statistics.
Childbirth--Economic aspects--United States--Statistics.
Health surveys--United States--Statistics.
Medical statistics--United States.
Pregnant women--Drug use--United States--Statistics.
Prenatal care--United States--Statistics.