Objectives: This study was undertaken to examine whether there is an association between parity and age at first birth and risk of pancreatic cancer. Methods: The study cohort consisted of all women with a record of a first and singleton childbirth in the Birth Registration System between 1978 and 1987. We tracked each woman from the time of their first childbirth and linked their vital status with mortality database. Cox proportional hazard regression models were used to estimate the relative risks (RRs) of death from pancreatic cancer associated with parity and age at first birth. Results: A trend of increasing risk of pancreatic cancer was seen with increasing age at first birth. The adjusted RR was 0.69 (95% confidence interval, 0.49-0.98) for women who born 2 children and 0.64 (95% confidence interval, 0.44-0.93) for women with 3 or more births, respectively, when compared with women who had given birth to only 1 child. There was a significant decreasing trend in the RR of pancreatic cancer with increasing parity. Conclusions: This study provides evidence that reproductive factors (parity and early age at first birth) may confer a protective effect on the risk of pancreatic cancer.
