Women should wait six months before trying for a baby with a new partner to cut their risk of a potentially fatal pregnancy condition, researchers have warned.

They urge women wanting to have a child not to use barrier methods in the months before conception to cut the risk of pre-eclampsia.

This allows longer for the sperm and maternal antibodies to build a tolerance

The research has been welcomed by health charities who say women can use the advice to help protect themselves and their babies.

Mike Rich, chief executive of Action on Pre-eclampsia, said that although the South African findings were not all new, that they did add to a growing body of research.

Protect

"It is interesting and good from our point of view.

"There is no cure for pre-eclampsia and very little treatment.

"Research like this which shows women can reduce their risk can only be a good thing."

Research like this which shows women can reduce their risk can only be a good thing

Mike Rich, of Action on Pre-eclampsia

Pre-eclampsia is caused when the woman's blood pressure increases sharply during the final weeks of pregnancy.

Not only can the pressure starve the foetus of oxygen, the condition, if left untreated, can develop into eclampsia, which can cause the mother to have fits, and can prove fatal.

Usually the woman is placed under close observation - the child can be delivered early if the condition worsens.

Study

Researcher Dr Gideon Verwoerd from the Department of Obstetrics and Gynaecology at Tygerberg Hospital and Stellenbosch University, said women were at a 60% greater risk if they didn't leave at least a six month period before conception.

Previous research had suggested that women who had already had children without suffering from pre-eclampsia could then experience it if they changed partner.

Waiting six months cuts risk

But Dr Verwoerd said that their study of 240 women showed that leaving a gap before conception could reduce any risks introduced by having a child with a new partner.

"We showed that the change of partner is not a major factor.

"We had thought that the change of partner per se was the risk factor."

But he said that a change of partner could even be a positive factor if the woman had previously suffered from pre-eclampsia.

The article was published in the International Journal of Gynaecology and Obstetrics.