Abstract
BACKGROUND: We examined the association between parity and risk of lung cancer. METHODS: The study cohort consisted of all women with a record of a first singleton birth in the Taiwanese Birth Register between 1978 and 1987. We tracked each woman from the time of their first childbirth to 31 December 2009. Follow-up was terminated when the mother died, when she reached age 50 years, or on 31 December 2009, whichever occurred first. The vital status of mothers was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) for death from lung cancer associated with parity. RESULTS: There were 1375 lung cancer deaths during 32 243 637.08 person-years of follow-up. The mortality rate of lung cancer was 4.26 cases per 100,000 person-years. As compared with women who had given birth to only 1 child, the adjusted HR was 1.13 (95% CI, 0.94-1.35) for women who had 2 children, 1.10 (0.91-1.33) for those who had 3 children, and 1.22 (0.96-1.54) for those who had 4 or more children. CONCLUSIONS: The findings suggest that premenopausal women of higher parity tended to have an increased risk of lung cancer, although the trend was not statistically significant.