Canada has fallen behind other countries in collecting statistics on the use of different contraceptives, and this has important public policy implications, according to some experts.

The situation is "in sharp contrast" to the U.S., Australia and many European countries, which collect national data on birth control, UBC professor and family physician Wendy Norman told CBC News.

She says there's a real information gap on reproductive health in Canada.

Dr. Norman is also one of the team leads at the Canadian Contraception Access Research Team (CART). She spoke to CBC News while attending the annual clinical meeting of The Society of Obstetricians and Gynaecologists of Canada in Calgary. She presented two papers at the meeting.

Also presenting was Dr. Dustin Costescu, an obstetrician/gynecologist who teaches at Queen's University in Kingston, Ont. Costescu is the current Contraception Advice, Research and Education Fellow at Queen's.He tells CBC News it's "an ongoing challenge to get uptodate information" on birth control trends. "We are trying to capture something that's experiencing a period of rapid change and I think new data would be helpful."

Attention is once again focused on contraception after CBC News this week reported that between 2007 and February 2013, doctors and pharmacists reported 600 adverse reactions and 23 deaths where oral contraceptive brands Yaz or Yasmin were suspected. That story is based on documents obtained from Health Canada.

- Read CBC's story on Yaz, Yasmin birth control pills suspected in 23 deaths

Dated or incomplete information

The information on trends in birth control in Canada that is publicly available appears to be dated or incomplete. There's relatively current information on some birth control methods — but not all — and information for some age groups but not all ages in the reproductive years.

The most recent complete data is based on a survey conducted seven years ago, which is even prior to Health Canada approving the use of Yaz as an oral contraceptive.

As a result, Dr. Costescu says, "We do use American data to estimate some of the trends in contraception because that data is collected more regularly." However, in some sigificant ways, birth control trends differ in the the two countries.

U.S. data from the Centers for Disease Control show that oral contraceptive pills and sterilization are the most popular methods of birth control there, followed by condoms. The methods used vary depending on age and race. Almost all women in the U.S. have used at least one form of contraception.

Recent data from Statistics Canada only covers 15- to 24-year-olds, and only some methods of contraception.

In 2012, the agency reported that the use of condoms among that age cohort had been increasing. In 2009-2010, about 67 per cent of 15- to 24-year-olds who were sexually active in the past year used condoms. The StatsCan report notes that for this group, condom use declined as they got older.

Half the women left out

According to Dr. Norman, Statistics Canada's population-based surveys aren't as well funded and resourced today. The data above comes from the Canadian Community Health Survey (CCHS) and Norman is critical of StatCan for reducing "the number of people they're asking sexual health questions of to just within the 15-24 range," which leaves out half the women in their reproductive years.

"We need that data," according to the UBC faculty of medicine professor.

"This is required for effective health system policy and planning and being able to promote excellence in reproductive health care," Dr. Norman told CBC News.

She would like to see StatsCan ask about the full range of birth control methods. The CCHS does not include long-acting reversible contraceptives, or LARCs, "the most effective and often the most acceptable for women and couples to employ," according to Norman.

One of the LARCS, intra-uterine devices, or IUDs, increased from 1 per cent in the U.S. to from five to eight per cent, Costescu notes, but solid data is not available for Canada. He does say that "most of us who do a lot of contraception work agree observationally that that's the trend we are seeing in Canada."

As part of a process now underway at StatsCan to perhaps put out a new and better survey on these issues, the agency requested Norman and her CART colleagues present a brief on how to improve the sexual behaviors module of the CCHS.

No one from Statistics Canada was available for an interview for this story.

Most recent data from 2006

In order to try and fill the gap in the StatsCan data, a group of scientists undertook a national survey that included questions on contraceptive methods.

The study, published in the Journal of Obstetrics and Gynaecology Canada in 2009 and based on data from a 2006 market research survey, found condoms, followed by oral contraception, were the most commonly used method of contraception. Withdrawal was number three, but it was the choice of far fewer women compared to the first two methods.

- Background on the options for pregnancy prevention

According to Norman, because the women surveyed were volunteers to a market research panel conducted online, it "falls short of the rigorous validation methods used by Statistics Canada" and surveys a group that on average is economically better off and better educated than the general population in Canada.

Alex McKay, the research cordinator for the Sex Information and Education Council of Canada (SIECCAN) in Toronto says, "we have a reasonably clear picture" of the trends in birth control uses in Canada. Despite being dated and incomplete, the findings from the various sources are fairly consistent.

Why birth control data is needed

Nevertheless, McKay tells CBC News, "The most important benefit from having good data on trends in contraception use is that women's ability to make informed contraceptive decisions has a very significant impact for them, particularly the ability to time conception for when it works best for the woman's life."

It's not at the personal level that the data matters most but at the health and public policy level.

"Contraceptive care really should be individualized to meet the patient's needs. While some patients like to know that what they're using is used commonly, it's actually more important for me to understand what someone's individual goals are., Costescu says.

Current data on birth control trends in Canada "will be essential for our governments to be able to make effective choices on health system care and to be able to lower health system costs," Norman argues.

"In countries like Canada, we know it costs more for the government to provide care for unintended pregnancies that go on to birth or to abortion than it would to subsidize all contraceptive methods, but in Canada we can't evaluate that." (About half of pregnancies are unintended at the time of conception and about half of those unintended pregnancies end in abortion, according to CART.)

One reason Norman and her colleagues created CART was to push for better information on these trends, in order to lower health-care costs. "At the moment our lack of information on birth control prevalence has been the number one reason that we've been unable to gather the data that would support these evidence-based decisions for the government."

That may change very soon. On June 21 the federal government's Canadian Institutes of Health Research will announce what new projects they will be funding. If CART's proposal is chosen, Norman says this Fall they will be undertaking a comprehensive, validated survey on birth controls, similar to that used in other nations, conducted through in-person interviews.