Globally, the number of maternal deaths remains large, and the risk per birth is high in the developing world. Deaths declined between 1990 and 2008, despite the 42% increase in women. We decompose selected determinants to help explain the decline. Numbers of women, births, and fertility rates come from the UN; maternal mortality ratios are from the UN and from Hogan et al. Decomposition isolates the effects of additional women, decreases in fertility, and declines in mortality ratios, also in rates. Women aged 15-49 increased by 42%, but births remained constant due to declining fertility rates. The fertility decline alone averted approximately 1.7 million deaths, 1990-2008. The risk per birth (MMR) also fell, adding to the decline in the number of deaths. Exceptional declines occurred in the maternal mortality rate. Sub-Saharan Africa has experienced minimal declines in deaths, due to increases in women and small declines in fertility and mortality. The growing numbers of women have made international efforts to reduce the number of maternal deaths ever more challenging. Comparatively little attention has been given to the offsetting effect of the historic fertility declines in the developing world, and hence a flat trend in births. The maternal mortality ratio has also fallen, reflecting the success of direct maternal health efforts. Programs that provide couples with the means to control their fertility can reinforce fertility declines. These programs are companions to ongoing, direct measures to reduce the risk of death once pregnant.