Cohort Fertility Patterns and Breast Cancer Mortality among U.S. Women

Patrick M. Krueger, University of Texas at Houston
Sam Preston, University of Pennsylvania

Epidemiological research has shown that women who have early births and numerous births have reduced risks of being diagnosed with breast cancer. We examine whether cohort fertility patterns are associated with breast cancer mortality rates in the U.S. We use negative binomial age-period-cohort models, and data from U.S. Vital Statistics and the U.S. Census to examine the relationship between breast cancer mortality rates among women aged 40 and older (in five-year age groups), and age-specific cumulative first birth rates, age-specific cumulative second birth rates, and completed birth rates at ages 35 to 39. Our results show that cohorts marked by higher rates of childlessness at ages 15 through 24, and lower cumulative second birth rates at ages 20 through 29, have higher rates of breast cancer mortality. Further, cohort fertility patterns appear to dampen the rise in breast cancer mortality rates in the 1970s through the 1990s.