Mechanisms for the Association of Maternal Age, Parity, and Birth Spacing With Infant Health

This Note reviews biomedical mechanisms connecting maternal age, parity, and birth spacing with infant mortality and assesses their likely importance in developing countries. This is partly to help refine estimates of the effects of family planning programs on infant health. Young maternal age by itself affects infant health mainly through associations with primiparity or short intervals or confounding effects of poverty. Short intervals between pregnancies are detrimental to fetal growth, though especially in low-mortality countries, this is partly an artifact of preterm delivery. High parity is associated with poor pregnancy outcomes and infant health partly through direct pathways and partly through confounding effects of poverty. Older maternal age is associated only with relatively rare conditions. Family planning programs targeted to high-risk pregnancies can improve infant health both through the direct and indirect pathways.