UK doctors say a treatment for heavy periods caused by fibroids can seriously harm a subsequent pregnancy.
An Elizabeth Garrett Anderson Hospital study looked at the outcomes of 215 pregnancies following uterine artery embolisation (UAE) treatment.
The researchers found much higher rates of miscarriage, caesareans and heavy bleeding after delivery, and call for caution in recommending the treatment.
The study appears in the journal, The Obstetrician and Gynaecologist.
UAE has been available as a treatment in the UK since 1995.
The doctors pulled together the data from five small studies carried out in the UK, Czech Republic and Canada.
Fibroids are small, benign lumps of smooth muscle in the womb.
Sometimes, because of their number, size and location, they cause heavy period pain or difficulty in getting pregnant and treatment is needed.
Doctors at the Elizabeth Garrett Anderson Hospital say as many as 40% of women of reproductive age have fibroids.
They found that the risk of miscarriage following UAE was 35% compared with a rate in untreated women of 10 to 15%.
The incidence of caesarean sections was much higher at 67% compared with a normal rate of 20 to 25%.
And bleeding after delivery was more than twice as common at 14% compared with 5%.
The babies tended to be smaller and they were more likely to present in an awkward position.
Ertan Saridogan, who led the research, said although a large number of women had already undergone the procedure, there had been relatively little study of its long-term effects.
He said: "We do not offer it as a first-time treatment, but, for some women, surgery and other treatments do not work.
"We want to increase awareness of the pitfalls of this widespread procedure.
"I hope this will inform women before they make their decisions, so they can make an informed choice - they've been going at it blindly without realising what it might imply for their future pregnancies."
Henry Annan, from the Royal College of Obstetricians and Gynaecologists, said he agreed that care should now be taken in recommending the treatment.
"A proper randomised controlled trial of this procedure would take many years - it's important that patients should have some idea of the pros and cons of all the various treatments for fibroids."