Let me complete the summary posted by the CBO:
Low birthweight is the primary risk factor for infant mortality and most of the decline in neonatal mortality (deaths of infants less than 28 days old) in the United States since 1970 can be attributed to increased rates of survival among low-birthweight newborns. Indeed, comparisons with countries for which data are available suggest that low birthweight newborns have better chances of survival in the United States than elsewhere. The U.S. infant mortality problem arises primarily because of its birthweight distribution; relatively more infants are born at low birthweight in the United States than in most other industrialized countries. Unfortunately, little progress has been made in reducing U.S. low birthweight rates, which would further improve infant mortality rates.
Federal and state initiatives to lower infant mortality rates have focused on strategies to reduce financial barriers that limit access to prenatal care and on strategies to expand the supply of prenatal care services available to poor pregnant women. The relative advantages and disadvantages of these and other policies to reduce low birthweight and infant mortality are the focus of considerable debate. Recent expansions of the Medicaid program are enabling more low-income children and pregnant women to obtain the health care that they need. Being eligible for Medicaid does not necessarily guarantee access to care, however, especially in areas where providers are in short supply.
Hence, federal programs that provide direct support for maternal and child health services and primary care for low-income populations are also important. **Some policy researchers believe, moreover, that the scope of strategies to reduce infant mortality should be broadened from a relatively narrow focus on pregnancy care to the more general issue of how to improve the health status of poor women and their families. **
Also there is the CDC reports:
cdc.gov/nchs/data/databriefs/db09.pdf