Women's Sexual Health Section

Six degrees of contraception

Are menstrual monitoring devices a viable alternative for the Pill � or just a fancy way of marketing the rhythm method?

By Susan Orr-Mongeau

At 25, Letitia Larivee decided it was time to trash the Pill and started shopping around for a new method of contraception. She figured since she was newly married, health-conscious, and financially secure she could take the chance on an alternative � and hormone-free � birth control. She eventually settled on a menstrual cycle monitoring device called Lady-Comp. Seven years later, at 32, she's still thrilled with her choice. "I think it's great. There are no pills and none of the guesswork of the manual charting methods," she says.

The temperature device basically applies the rules of the body temperature method but uses a mini-computer to record and store data. A woman takes her body temperature orally using a temperature sensitive probe that's connected to a small computer and then enters information about her menstrual dates which are compared with more than 700,000 other cycles stored in the computer. A calculation is done that predicts fertility for the next 24 hours (and the following 6 days) by displaying a colour; red is fertile and green is infertile.

Ms Larivee isn't alone in her quest to get off the ever-popular oral contraceptive (OC), currently used by 32% of sexually-active women. Many women get fed up with the weight-gain, and breast cancer and HRT stories in the news have made many of them worry about taking hormones. But natural methods of birth control are still relatively unpopular in Canada; withdrawal accounts for 6% and the Vatican's favourite, the rhythm method, gets a mere 2% following � probably due to its notorious unreliability. There are no stats available on how many Canadian women are using monitoring devices.

A SCEPTIC'S VIEW
Vancouver Ob/Gyn Dr Timothy Rowe, one of the principal authors of the new practice guidelines for contraception from the Society of Obstetricians and Gyneacologists of Canada, isn't especially keen on these monitors. "They're just a grand extension of BBT [basal body temperature]," he says. "They're using indirect indices of ovulation, which don't reliably predict ovulation."

These types of monitors have been on store shelves in Europe for about 15 years and seven years in Canada, but their efficacy varies tremendously � as do their price tags. The monitors can run anywhere from $175 to $600. There's also an inconvenience issue � since a woman is usually fertile about eight days out of each month, she and her partner are forced to use another contraception, preferably a barrier method like condom or diaphragm.

Dr Rowe adds that he wouldn't recommend the menstrual cycle monitors to his patients because, "There's very little scientific evidence available on these devices." A recent German study published in Journal of Human Reproduction has partially filled this gap. The study found that about 10% to 15% of women of reproductive age in Europe use variations of natural family planning methods. An estimated 30% to 40% of those women are relying on some type of menstrual cycle monitor to detect their fertility window, usually for birth control purposes, but also sometimes to optimize their chances of conceiving (incidentally, Lady-Comp's manufacturers also market a virtually identical fertility monitor called Baby-Comp).

The research team, led by emeritus professor Dr Guenter Freundl, tested three types of monitors in their pilot study involving 62 women and a total of 122 menstrual cycles. They found that monitors based on microscopic evaluation of saliva or cervical mucus showed higher rates of falsely indicating infertile days than the temperature or hormonal computers. The three temperature monitors tested performed reasonably well with 1.7%, 4.7% and 7.5% false negatives.

NOT FOR FORGETFUL JANES
Like most contraceptive methods, reliability depends on correct and consistent use. Considering the high failure rate of these monitors � basically a high-tech form of the rhythm method � they're probably only for your mature, educated, disciplined and wealthy patients who want to get off the hormone treadmill. But advise them to keep a pack of Trojans by the bedside, just in case.