Preterm Births are those at under 37 weeks gestational age.
Low Birth Weight are babies delivered at under 5lb 8oz (2500g).
Cesarean Births are "C-section" deliveries. The Healthy People 2020 target rate is 23.9% for low-risk, first-time mothers.
Healthy People 2020 is a set of 10-year objectives for the US. See healthypeople.gov.
Healthy People 2020 defines a health disparity as a health difference that is closely linked with social, economic, and/or environmental disadvantage.
Sources
1Preterm, low birth weight, and cesarean rates for each county and demographic: Centers for Disease Control and Prevention. National Center for Health Statistics. VitalStats (accessed February 10, 2012).