In this paper we explore the relation between changes in reproductive behavior, such as those that might result from an effective family planning program in developing countries, and changes in child and maternal mortality. Specifically, we use the results from recent multivariate studies to estimate the changes in mortality that might result from altering maternal age, birth order, and birth spacing distributions of live births. Our results indicate that if childbearing were confined to the "prime" reproductive ages of 20-34, then infant and child mortality rates would fall by about 5 percent. Limiting childbearing to ages 20-39 may also reduce the maternal mortality ratio by 11 percent. The elimination of fourth and higher order births would reduce the maternal mortality ratio by about 4 percent. Universal adoption of an "ideal" spacing pattern in which all births subsequent to the first are spaced at least two years apart may reduce infant mortality by about 10 percent and child mortality by about 21 percent.