The contribution of contraception to reductions in obstetric mortality and morbidity is universally acknowledged. One major pathway is by reducing the number of unwanted births. Each pregnancy and childbirth carry a health risk for the woman, and where obstetric services are poor, maternal mortality is still very high. In most Asian and Latin American countries for which relevant evidence exists, it is estimated that about 20% of births were unwanted at the time of conception. In Africa, where desired family sizes tend to be relatively high, the prevalence of unwanted births is typically lower, closer to 10%. On the assumption that unwanted births carry the same risk to the health of the mother as wanted births, it has recently been estimated that the global burden of disease attributable to unwanted births amounts to 4.6 million disability-adjusted life years (DALYs) (Collumbien et al., 2002). Better use of effective contraception would reduce this substantial burden. In the extreme scenario, where all women who wanted to stop having children used effective methods of contraception, the burden would be eliminated, but for a small residue resulting from contraceptive failure.