Young men whose parents had difficulty in conceiving are likely to have relatively poorer sperm quality than others. Genes play an important role in sperm development, but the extent to which heredity contributes to male infertility is not clear. A few studies have found poor semen quality in sons whose mothers have received fertility treatment, but it is unknown whether infertility is caused by hereditable factors. Danish researchers examined whether sons of sub-fertile couples who had not received fertility treatment had poorer semen quality than sons of fertile couples. They studied 311 men aged between 18 and 21 years. In most cases, the men's parents had taken 6 months or less to conceive, but 11 percent were born to parents classified as sub-fertile as they took more than a year to conceive. It was noted that those whose parents took longer than one year to conceive (without any fertility treatment) tended to have a lower sperm count and fewer normal-looking sperm. Moreover, men with sub-fertile parents had a 22 percent lower sperm concentration. The findings are consistent with the notion that fertility problems have at least some heritable causes. The study was not able to ascertain whether the poorer sperm quality might be related to inherited factors from the father, mother or both. Since the findings are based on a small number of men, further research is needed to confirm the results.
American Journal of Epidemiology
June 2008