It is widely recognized that family planning contributes to reducing maternal mortality by reducing the number of births and, thus, the number of times a woman is exposed to the risk of mortality. Here we show evidence that it also lowers the risk per birth, the maternal mortality ratio (MMR), by preventing high-risk, high-parity births. This study seeks to quantify these contributions to lower maternal mortality as the use of family planning rose over the period from 1990 to 2005. We use estimates from United Nations organizations of MMRs and the total fertility rate (TFR) to estimate the number of births averted-and, consequently, the number of maternal deaths directly averted-as the TFR in the developing world dropped. We use data from 146 Demographic and Health Surveys on contraceptive use and the distribution of births by risk factor, as well as special country data sets on the MMR by parity and age, to explore the impacts of contraceptive use on high-risk births and, thus, on the MMR. Over 1 million maternal deaths were averted between 1990 and 2005 because the fertility rate in developing countries declined. Furthermore, by reducing demographically high-risk births in particular, especially high-parity births, family planning reduced the MMR and thus averted additional maternal deaths indirectly. This indirect effect can reduce a county's MMR by an estimated 450 points during the transition from low to high levels of contraceptive use. Increases in the use of modern contraceptives have made and can continue to make an important contribution to reducing maternal mortality in the developing world.