Sperm plays a more complicated role in the mating game than first thought, researchers at Australia's University of Adelaide said Wednesday.
Professor Sarah Robertson, from the University's Robinson Institute, said sperm "communicates" with the female reproductive tract and helps prepare the female body for nurturing a fetus. If the female system does not approve of the sperm's message, it could attack them.
"We have discovered that sperm doesn't just fertilize an egg," Robertson said. "It actually contains signaling molecules that are responsible for activating immune changes in women so they can accept a foreign substance in the body — in this case, sperm — leading to conception and a healthy pregnancy."
Researchers found that, similar to humans, not all male sperm is good at communicating and some female bodies have very high standards.
"The male provides the information that increases the chance of conception and progression to pregnancy, but the female body has a quality-control system which needs convincing that his sperm is compatible and also judges whether the conditions are right for reproducing," Robertson said.
The information could prompt researchers to look at ways of encouraging a woman's body to better tolerate her partner's semen if they are having trouble becoming pregnant.