Kristian Jorgensen of the Statens Serum Institut in Copenhagen, Denmark, used a national population-based register to analyze data from all men born in Denmark from 1935 to 1988 -- 3,400 developed prostate cancer.

The study, published online ahead of the Feb. 15 issue of the journal Cancer, found men without children were 16 percent less likely than those with children to be diagnosed with prostate cancer after up to 35-years of follow-up.

The study also found that among fathers, there was a gradually reduced prostate cancer risk with an increasing number of children.

The authors speculate that this might reflect a "healthy father" phenomenon -- men who retain fertility are less likely to develop a malignancy.

The researchers found no association between prostate risk and child gender.