The IUD, the most effective form of reversible birth control, is making a comeback after decades gathering dust on pharmacy shelves.

Although the pill, used by almost a third of sexually active women, is still most popular, doctors are reporting more and more requests for intrauterine devices (IUDs), small, flexible, T-shaped frames inserted into the uterus by a doctor.

“We are putting them in more women, and in more younger women,” says Dr. Dara Maker, co-medical director at the Bay Centre for Birth Control and a family doctor at Women’s College Hospital.

A 2009 study led by Dr. Sheila Dunn, research and program director for the Bay Centre for Birth Control, found IUD insertion rates in Ontario have been on the rise since 2001, particularly among women aged 25 to 39.

Still, only between 1 and 3 per cent of Canadian women choose the IUD, while in Europe, as many as 25 per cent rely on them to prevent pregnancy. Some doctors blame that gap on lingering concerns about the IUD’s safety and efficacy after the Dalkon Shield scandal of the 1970s.

The Dalkon Shield was an IUD model whose faulty design led to a disproportionate number of cases of pelvic inflammatory disease, ectopic pregnancies, and even death. The model’s tailstrings, which hung down into the vagina, were made of multiple strands wound together that allowed bacteria to “wick” up into the uterus. Lawsuits were filed against its manufacturer and it was eventually pulled off the market.

The new models available in Canada are not associated with those problems, because the strings are made of a single strand. There are two kinds of IUDs on the Canadian market, both of which are inserted into the uterus for up to five years: copper models called the Flexi-T and the Nova-T, and a hormone-releasing model called the Mirena.

Copper IUDs, in which a smooth wire is wound around the plastic frame, work by altering the chemistry of the womb, making it a toxic environment for sperm, though doctors still aren’t sure of the exact mechanism. The plastic frame of the Mirena contains a barrel of slow-release levonorgestrel, which prevents pregnancy in multiple ways, primarily by increasing the amount of mucus in the cervix, which blocks sperm, and lessening the thickness of the uterine lining, making it difficult for a fertilized egg to become implanted. They can be removed at any point with no impact on fertility.

The devices are so effective that the failure rate (around 1 per cent for copper IUDs and less than 1 per cent for the Mirena) is comparable to tubal ligation (between 1 and 2.5 per cent). Unlike the pill, “the beauty of the IUD is that it doesn’t depend on the user,” says Dunn of the Bay Centre for Birth Control.

Yet “there’s not as much awareness about the IUD as there could be, particularly among younger women,” says Dr. Erica Weir, associate medical officer of health for York Region.

That could be because, as research suggests, misinformation is widespread among doctors. One 2008 study of Kingston, Ont., family physicians’ perceptions about IUDs found a huge gap between doctors’ beliefs and the current clinical guidelines.

More than two-thirds of the 96 respondents said they would not recommend IUDs to women who had not given birth, despite well-accepted guidelines from the World Health Organization and the Canadian Contraception Consensus that put very few restrictions on their use.

Even though IUDs are 99 per cent effective or better, between 38 and 47 per cent of respondents believed failure was a “major” risk.

More than 60 per cent thought pelvic inflammatory disease was a “major risk” with the current IUD models, though the infection risk increases only slightly for the first month after insertion and afterwards is the same as that of the general population.

“The results were quite striking,” says Dr. Esther Stubbs, a study author who has had a family practice in Belleville for the past four years. “I was quite surprised at how big the misperceptions were.”

Doctors who had been practicing for 20 years or longer were less likely to prescribe IUDs than younger doctors, the study showed. International research also shows that urban doctors are more likely to prescribe IUDs to young, childless women than rural doctors. Stubbs expects the situation in Kingston would be much the same in most Canadian urban centres.

“Some of the myths have been dispelled,” says Maker. “It just takes a long time to filter through to the general population, and even the medical field.”

Stubbs wants to encourage even younger women to consider using IUDs.

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“A lot of people think the (IUD) is good for people that are married, and people that have had a few kids, but we want to encourage teenagers to think of it as well to decrease the teen pregnancy rate.”

Dr. Jennifer Blake, chief of obstetrics and gynecology at Sunnybrook Health Sciences Centre, thinks there are more women who could benefit from it.

“For women who have not thought that this is not an option for them, it’s worth a second look.”