Associations of parity and age at first pregnancy with overall and cause-specific mortality in the Cancer Prevention Study II

Objective: To evaluate the association of parity, number of live births, and age at first birth with mortality using multivariable-adjusted Cox proportional hazards regression models. Design: Observational cohort. Setting: Not applicable. Patient(s): A total of 424,797 women. Intervention(s): None. Main Outcome Measure(s): All-cause and cause-specific mortality. Result(s): During median follow-up of 24.93 years, 238,324 deaths occurred. Parous, compared with nulliparous, women had lower rates of all-cause (hazards ratio [HR] = 0.94, 95% confidence interval [CI] 0.93-0.96) mortality, driven by heart disease and overall cancer mortality. A linear trend was found for more births and diabetes mortality (P < .001) with having R6 births, compared with 2, associated with an HR of 1.28 (95% CI 1.15-1.43). Compared with age at first birth from 20-22 years, age at first birth < 20 years was associated with higher mortality rates overall (HR = 1.04, 95% CI 1.02-1.06), driven by heart disease and chronic obstructive pulmonary disease mortality; whereas, R35 years was associated with higher overall cancer mortality (HR = 1.13, 95% CI 1.06-1.20). Conclusion(s): Although parity was associated with a slight reduction in rates of all-cause mortality resulting in a minimal impact on average lifespan, the higher diabetes mortality in grand multiparous women might warrant continuous monitoring, particularly for abnormal glucose metabolism, among these women. (C) 2016 by American Society for Reproductive Medicine.