Comparing semen characteristics of men with subfertile and fertile parents.

MedWire News: Danish researchers have strengthened the evidence indicating that infertility is partly inherited.

Previously, a few studies reported poor semen quality in men whose mothers had fertility treatment, but it was unclear whether this was due to the parents’ subfertility or the infertility treatment itself.

In the current study, Cecilia Ramlau-Hansen (Aarhus University Hospital) and colleagues compared the semen characteristics of sons of subfertile couples who did not undergo fertility treatment and sons of fertile couples.

The findings, based on 311 men, show that semen volume and sperm count were both significantly inversely associated with the parents’ waiting time to pregnancy.

Average semen volumes of sons of subfertile parents, defined as those who took at least 1 year to conceive, were 19 percent lower than those of sons whose parents conceived within 0-6 months, the team reports.

Sons of subfertile parents also had, on average, a 22 percent lower sperm concentration and a 23 percent lower proportion of morphologically normal sperm than the others.

Ramlau-Hansen et al say the results suggest “a small-to-moderate effect of parental subfecundity on semen quality in sons, comparable with the hypothesis that low fecundity has at least partly heritable causes.”