Childless men are less likely to develop prostate cancer than those who are fathers, Danish research suggests.
Conversely, having more children appears to lower the risk of prostate cancer in fathers.
But researchers found no evidence to back previous findings that fathering daughters was associated with an increased risk of prostate cancer.
Data on one million men born in Denmark between 1935 and 1988 were analysed for the study. The men were followed up between 1968 and 2003, and 3,400 cases of prostate cancer were identified in the Danish Cancer Registry.
Men without children were found to be 16 per cent less likely to develop prostate cancer than men with children.
Fathers had a 5 per cent reduction in prostate cancer risk for each additional child that was born, although the gender of the child seemed unimportant.
Lead researcher Dr Morten Frisch, from the department of epidemiology research at the Statens Serum Institute in Copenhagen, said that the findings may reflect a 'healthy father' phenomenon in which men who retain fertility are less likely to develop a malignancy.
It has been suggested that 'lower androgen levels in infertile men could explain the lower risk of prostate cancer in the group of childless men', he added.
'Further studies are required to identify the factors that explain the differences in prostate cancer risk,' said Dr Frisch.
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