This study examined low birth weight and infant mortality in the 50 states and the 54 largest American cities between 1979 and 1984. Its findings confirm that progress in reducing low birth weight and infant mortality has slowed, and in some cases the progress has actually reversed. Some states and many cities had higher rates of low birth weight and infant mortality in 1984 than in 1979. The disparity in low birth weight and infant mortality rates between nonwhites and whites is great, and from 1979 to 1984 this gap increased in most of the largest cities and in many of the states. While race can be used as an indicator of low birth weight and infant mortality, the causes are more likely the result of socioeconomic factors. Although many factors contribute to problems of low birth weight and infant death, poverty is the common element in all cases. The lack of money to purchase food, to receive proper medical care, to stay in school, and to afford adequate housing can act alone or together to harm the growth of the fetus in the womb and the growth and development of the infant during its first year. Further progress toward solving the problems of low birth weight and infant mortality must come from efforts to alleviate poverty and its harmful influence on infant health. Statistical data in tables and graphs are presented for each city and each state studied. Comparative analyses and trend analyses are presented in 43 tables and 4 maps. The appendices include a directory of sources for state vital statistics, and a list of 25 references. (FMW)