The relation of lifetime reproduction to survivorship in women and men: A prospective study.

The relation of lifetime reproduction to survivorship was investigated among 1,533 women and 1,230 men from Southern California who were born between 1880 and 1929. Analyses used the total group and two 25-year birthyear subcohorts (1880-1904 and 1905-1929). Follow-up for vital status was 100% and included 41,399 person-years, from baseline (1972-1974) through mid-1990. Cox proportional hazards analyses were adjusted for age, body mass index, estrogen use in women, and socioeconomic status. Alternate sets of analyses for each sex used reproduction coded dichotomously, and as a continuous variable. Parous women had significantly poorer survivorship than nulliparous women in the total group (P = 0.003) and among women born 1880-1904 (P = 0.02), but not among women born 1905-1929 (P = 0.08). Analyses using number of biological children showed significantly poorer maternal survivorship "per child ever born" among the total group of women (P = 0.04) and among women born 1880-1904 (P = 0.01), but not among women born 1905-1929 (P = 0.96). Further analyses confirmed that women's risk per child tended to increase with maternal age. Equivalent sets of analyses for men showed no relationship between reproduction and survivorship. The survivorship differences between women's birthyear subcohorts may be due to secular trends or age-specific disease patterns. Study findings tend to support the latter, and suggest that childbearing may increase or accelerate women's mortality from certain diseases which occur late in life, and that risk may increase with age. © 1996 Wiley-Liss, Inc.