Age at first birth, health, and mortality.

The biodevelopmental view sees the readiness and soundness of the organism at the time of first birth as its prime link to health and survival years and decades later. It suggests an optimum age at first birth shortly after puberty. The biosocial view emphasizes social correlates and consequences of age at first birth that may influence health and survival many years later. It suggests that better health and survival come from delaying motherhood as long as possible, perhaps indefinitely. Analyses consistently find patterns more in keeping with the biosocial view in a U.S. national sample of women ages 25 through 95. The fitted curves show high levels of current health problems among women who first gave birth in or shortly after puberty. Problems drop steadily the longer that first birth was delayed, up to about age 34, then rise increasingly steeply, particularly after about age 40. For women currently of the same age, the ratio of health problems expected given first birth under age 18 versus around age 34 equals that from currently being 14 years older. Health problems rise steeply with length of having delayed beyond age 40. Mortality hazard also declines with having delayed first birth well beyond the end of puberty. The ratio of mortality hazard between mothers with teenage versus late first births equals that from a 10-year difference in current age. Comparison to nonmothers of similar age and race/ethnicity shows that the correlation of motherhood with health problems and mortality hazard switches from detrimental to beneficial with delay beyond about age 22.