Fertility and offspring sex ratio of men who develop testicular cancer: a record linkage study

Analysis of associations between testicular cancer, subfertility and offspr ing sex ratio (proportion of males born among newborns) was performed on 35 30 Danish men, born 1945-1980, who developed testicular cancer in the perio d 1960-1993, As the basis of comparison we used the total population of Dan ish men born in the period 1945-1980 (n = 1 488 957) and their biological c hildren (n = 1 250 989), Men who developed testicular cancer had, prior to the cancer diagnosis, a reduced fertility (standardized fertility rate rati o: 0.93, 95% confidence interval: 0.89-0.97) and a significantly lower prop ortion of boys (48.9%, P = 0.02) compared with the general population (51.3 %). The reduction in fertility was more pronounced in men with non-seminoma but the reduction in offspring sex ratio was independent of histological t ype. This confirms earlier results from less conclusive studies and indicat es that testicular cancer, male subfertility and a female-biased sex ratio among new-born infants are characteristics of male reproduction that are li nked by biological mechanisms.