PHILADELPHIA (CBS) - We know that infertility affects about 14% of the world’s population, and the cause of infertility is split about 50-50 between male and female partners.

There is new information about potential reasons for infertility in the male. Of course we know the major cause of male infertility is often a low sperm count, or abnormal sperm motility or morphology, but researchers from University California Davis have identified a new cause – a genetic variation not uncommon in both European and Chinese men.

Turns out that if men have a particular variant of a gene called defb126, their sperm have an 84% reduced ability to move through cervical mucus. The mucus can slow the progress of damaged or imperfect sperm thereby reducing their likelihood of ever reaching and fertilizing the egg.

The authors found that wives of men with this genetic variation were much less likely to become pregnant and were 30% less likely to actually give birth compared to wives of men without the genetic variation.

Reported By Dr. Brian McDonough, KYW Newsradio Medical Editor