Observed variation between populations in fertility-timing distributions has been thought to contribute to infant mortality differentials. This hypothesis is based, in part, on the belief that the 20s through early 30s constitute "prime" childbearing ages that are low-risk relative to younger or older ages. However, when stratified by racial identification over the predominant first child-bearing ages, maternal age patterns of neonatal mortality vary between groups. Unlike non-Hispanic white infants, African-American infants with teen mothers experience a survival advantage relative to infants whose mothers are older. The black-white infant mortality differential is larger at older maternal ages than at younger ages. While African Americans and non-Hispanic whites differ on which maternal ages are associated with the lowest risk of neonatal mortality, within each population, first births are most frequent at its lowest-risk maternal ages. As a possible explanation for racial variation in maternal age patterns of births and birth outcomes, the "weathering hypothesis" is proposed: namely, that the health of African-American women may begin to deteriorate in early adulthood as a physical consequence of cumulative socioeconomic disadvantage.