A bladder infection may actually protect pregnant women from stillbirth, a study suggests.

It is a little simplistic to say that urinary tract infection is protective

Ruth Fretts Harvard Medical School

Researchers in Norway believe women with urinary tract infections (UTIs) or cystitis may be 70% less likely to have an unexplained stillbirth.

The finding, which goes against general medical thinking, suggests the bacteria may have a protective effect on the developing foetus.

The researchers believe their discovery could help scientists to develop an effective treatment to protect against stillbirths.

However, they warned that UTIs can still cause serious problem during pregnancy not least because they can restrict the growth of the foetus.

Common link

Dr Frederik Froen and colleagues at the University of Oslo looked at 241 stillbirths and 582 healthy births in Norway.

They were trying to discover a common link between unexplained stillbirths. They were expecting to find that women in poor health or with complications during pregnancy would be most at risk.

However, their discovery that UTIs may actually protect against stillbirth took them by surprise.

"That was really quite surprising," Dr Froen told New Scientist magazine. "If anything, it was the opposite of what we were expecting.

"It's against everything that you can find in any textbook."

The discovery led the researchers to speculate on the possible protective effects of UTIs.

But Dr Froen said that further study is needed and that it was merely a theory at present.

He added that there was no question of taking the theory forward with women at the moment.

"Of course, we cannot suggest that high-risk mothers should be given antibodies to protect the foetus based on this study alone," he told New Scientist magazine.

However, other experts raised doubts about the theory.

Ruth Fretts, an expert on unexplained stillbirths at Harvard Medical School, said: "It is a little simplistic to say that urinary tract infection is protective."