Sperm holds key to healthy pregnancy

A man's sperm can contribute to a healthy pregnancy but also runs the risk of being rejected if not entirely compatible with his partner, new research has found.

University of Adelaide Professor Sarah Robertson said semen had special qualities that contributed to a healthy pregnancy, including helping to prepare the female body for nurturing the fetus.

But some sperm fail to communicate with the female reproductive tract and while a man can appear to be fertile, his semen can be rejected if the woman's body doesn't consider it compatible.

"We used to think that if a couple couldn't get pregnant, and the mans semen test was normal, the problem lay with the woman," Professor Robertson said in a statement on Wednesday.

"But it appears this is not always the case.

"We have discovered that sperm doesn't just fertilise an egg.

"It actually contains signalling 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.

"It's rather like a two-way dance."

Professor Robertson, a fertility specialist, is leading a national research project examining the actions of semen in the cervix and uterus after intercourse takes place.

That research has revealed the male body provides information that increases the chances of conception and progression to pregnancy, but the female body has a quality control system which needs convincing that the sperm is compatible, and also judges whether the conditions are right for reproducing.

"That's where the dance can go wrong with some couples if the male signals are not strong enough, or if the female system is too choosy," Professor Robertson said.

"If we can understand the cascade of events which come into play when the sperm enters the female reproductive tract, we may be able to mimic or assist this with new therapies, encouraging tolerance of her partner's semen, for those couples who are experiencing difficulties becoming pregnant."

Professor Robertson is seeking female participants for her ongoing research, which is funded by the National Health and Medical Research Council.

Women aged 18-40 who have had a tubal ligation but are sexually active and in a stable relationship are needed for the study.

They cannot be using any other contraceptives and their partners must not have had a vasectomy.

Professor Robertson said the study was the first of its kind in Australia and would increase knowledge of the importance of semen for reproductive health, hopefully leading to improved treatments for infertility and miscarriage.