TORONTO - Planned caesarean section births in Canada carry a three-fold greater risk of severe complications than planned vaginal births, researchers reported Monday in the Canadian Medical Association Journal.

Fortunately the rate of serious problems arising from either type of births is low in this country. But as increasing numbers of women choose C-sections to deliver their babies, they ought to have the full facts before them, the study suggested.

"Pregnant women and physicians should be aware of these potential risks when contemplating an elective caesarean delivery, and their decisions should be based on the risks and benefits for mother and infant alike,'' said the authors, who are from a variety of universities and teaching hospitals in Vancouver, Halifax, Calgary, Montreal and Winnipeg.

The lead author was Dr. Shiliang Liu, of the Public Health Agency of Canada's health surveillance and epidemiology division.

A commentary accompanying the article reflects the conundrum medical authorities face as more women and their doctors opt to bring babies into the world by surgical means.

On the one hand, there are increased risks that raise questions about going this route when the procedure is elected, not required. But conversely, C-sections have lowered rates of stillborn births and reduced the number of deliveries in which forceps are used. The use of forceps also carries potential complications.

"We're living in a time of technology when the expectation is that everything can be planned, everything can be figured out, nothing can be left to chance,'' Dr. Anthony Armson, the author of the commentary, said in an interview.

"So I think the trend will continue.''

Rates of C-section births have soared in Canada. In 2003, they made up 25.6 per cent of all births, up from 5.2 per cent in 1960.

Studies attempting to see if the move to elective C-section births is producing more delivery complications have shown mixed results.

Even the authors of this one suggest the best way to answer the question would be to randomly assign women expected to have low-risk deliveries to either have a caesarean section or deliver vaginally. But the authors acknowledge it might be hard to get an ethics board to approve such a study. And getting enough women to agree could also be problematic.

So in this study, the authors viewed birth records for all provinces (except Quebec and Manitoba) from April 1991 to March 2005, comparing the rates of complications in women who had a C-section because the fetus was in the breech position (considered a low-risk C-section delivery) with women who had a vaginal delivery.

They classified serious complications as things like hemorrhage requiring hysterectomy or blood transfusion, uterine rupture, reactions due to anesthetic and surgical wound infections, among others.

There were 27.3 cases of complications per 1,000 women who gave birth by C-section compared to nine per 1,000 in women who gave birth naturally.

"When you say 3.1 times (higher), that sounds pretty significant. But in fact, because the rates are so low anyway, even a three-fold increase ... (is) still pretty low,'' said Armson, who is director of the maternal, infant and reproductive health research at Toronto's Women's College Research Institute.

A variety of factors -- some medical, some lifestyles -- are involved in the trend towards more C-section births.

Armson noted that medicine can now better identify pregnancies that might end in a tricky delivery and step in to circumvent potential problems. As well, many women are waiting till they are older -- and therefore at higher risk of delivery complications -- to have babies. And more expectant women start out overweight, which also increases risks.

With delivery problems the number 2 cause of medical malpractice suits, some doctors are quicker to propose C-sections if there is any sense the birth might not be completely straightforward. Some expectant parents like the notion of being able to rally family around for a planned delivery. And some women want to avoid the pain of childbirth.

Highly publicized celebrity C-sections _ the so-called too-posh-to-push crowd _ are also fuelling the movement, Armson said, though he doesn't believe it is the major driver of this trend.

"Certainly there's no question there's an increasing demand for elective caesarean section or planned caesarean section . . . although I don't think it's reached the proportions where it is anywhere near the primary reason for caesareans,'' he said.