Many women who give birth have an episiotomy -- a cut made in the vaginal wall, done just before the baby is born in order to enlarge the birth passage.

Until recently, this surgical procedure was a routine part of childbirth for most Canadian women, especially first-time mothers. Doctors believed that episiotomy prevented vaginal tissue from tearing and pelvic muscles from being weakened by excessive stretching. Also, because it reduced vaginal stretching, episiotomy was thought to preserve sexual enjoyment.

But in the late 1980s, spurred by women's growing criticism of routine episiotomy, researchers started to take a closer look at this practice. Since then, study after study has found that far from providing benefit, routine episiotomies actually do more harm than good.

Women who have episiotomies report more pain and more problems with sexual, urinary and bowel function, says Dr. Michael Klein, a professor of family practice and pediatrics at the University of British Columbia and the author of major North American studies on episiotomy.

These women also have more severe tears in the perineum (the area between the vagina and the anus). So, in fact, episiotomies cause, rather than prevent, perineal tears.

"If you take into account the reasons why women might require an episiotomy -- such as a big baby, a long second stage of labour, or use of forceps or vacuum -- studies show that a woman is still 20 times more likely to have a third or fourth-degree tear in the presence of an episiotomy," Dr. Klein says.

Some experts compare the effect of an episiotomy to what happens when you cut a piece of fabric -- once a cut is started, the fabric rips easily.

That's especially true for a so-called median episiotomy -- a cut that extends from the bottom of the vagina towards the rectum, as opposed to a mediolateral episiotomy, which angles off to the side. A 1997 study from Laval University in Quebec City confirmed that median episiotomies are strongly linked to severe vaginal tears in women giving birth for the first time.

But according to Dr. Klein, in most cases neither a median nor mediolateral episiotomy is required. "It's not one versus the other," he says. "It's neither."

Today, doctors are being encouraged to do episiotomies only when they are deemed necessary -- for example, if the baby shows signs of distress and needs to be born quickly, or if the perineal tissue shows signs of major tearing. This is known as selective or restrictive episiotomy, and it has led to a dramatic drop in the rate of episiotomies in Canada. In 1981-82, 67 per cent of women giving birth had an episiotomy, compared with 38 per cent in 1993-94.

"I use episiotomies when I must -- when the baby must be rapidly delivered, or when I can't do a forceps or vacuum delivery without an episiotomy," says Dr. Klein.

Many doctors assume an episiotomy is necessary for forceps or vacuum deliveries, but Dr. Klein says that's not always the case. "We're asking physicians to think about what they do, instead of using a predetermined package of interventions."

According to a 1998 study that involved researchers from the United States, Britain and Canada, the case for restricting use of episiotomy is conclusive. "When a routine episiotomy is done, there is automatically trauma to the perineum," explains Dr. Walter Hannah, a study author and professor emeritus of obstetrics and gynecology at the University of Toronto.

"But when doctors follow a policy of restricted episiotomy -- making a cut only when deemed necessary -- more women are able to deliver their babies with an intact perineum."

This is true even though more spontaneous tears occur when episiotomy is not done. About half of women giving birth for the first time will experience vaginal or perineal tears requiring stitching, says Dr. Klein. About 25 per cent of women will tear during a subsequent birth. But overall, more women have an intact perineum when doctors restrict the use of episiotomy.

Other techniques that minimize perineal trauma include slowing descent of the baby's head until the perineal tissues have time to stretch, flexing the baby's head, and delivering the baby between contractions. Perineal massage also shows promise -- a 1999 study found that women who massaged their perineums daily for 10 minutes starting in the 34th or 35th week of pregnancy had a better chance of delivering with an intact perineum, especially if it was their first vaginal delivery.

If you don't want to have a routine episiotomy, Dr. Klein suggests telling your doctor.

It's important to know that in some circumstances, episiotomy is the best option for mother and baby. If you do require an episiotomy during delivery, a local anesthetic may be given before the incision is made. After delivery, the cut will be sutured with dissolvable stitches. You can expect some pain for a few days and possibly longer. For relief, try hot baths, ice packs or over-the-counter pain medication such as acetaminophen.