Parenthood after cancer - a population-based study.

Many cancer forms today have good prognosis, and parenthood after cancer diagnosis and treatment has become a central research topic. Previous research has mainly focused on reproductive cancers, and few population-based studies exist. The effect of several cancer forms on fertility at a population level was explored. Discrete-time hazard regression models were used to analyse register and census data for complete Norwegian birth cohorts. Men and women 17-44 years in the period 1965-2001 were included. Models for first- and higher-order birth rates, for men and women, were estimated.Overall, first-birth rates among persons with cancer were reduced by only about 25% when compared with the general population. Male cancer survivors' second- and third-birth rates were similarly reduced, whereas higher-order birth rates for females were 36% below those of the general population. Significant decreases in cancer survivors' fertility disadvantage relative to the general population were seen from 1965 to 2001. Reductions in fertility were most pronounced for reproductive cancer forms, presumably related to subfecundity. However, also cancer forms unrelated to reproductive function led to reduced fertility, perhaps suggesting underlying social mechanisms. This is further supported by the difference in probability between first and subsequent births observed for women. (c) 2007 John Wiley & Sons, Ltd.