Infertility is on the rise in Canada, according to the first study in nearly two decades to measure the proportion of Canadian couples who are having difficulty conceiving.
The researchers didn't set out to discover why the numbers are increasing. But possible explanations range from the growing number of women who are pushing back pregnancy ever later in life, to rising rates of obesity and heavy drinking among women, to declining sperm counts in men — though experts aren't convinced about that final factor.
The use of assisted-procreation technologies has increased dramatically over the past decade, yet "little is known about the prevalence of infertility in the population," the authors write in the journal, Human Reproduction.
The research was supported by funding from Assisted Human Reproduction Canada, a federal agency. The lead author is from Statistics Canada.
According to their estimates, up to 16 per cent of heterosexual couples where the woman is age 18 to 44 are experiencing infertility — a near doubling since the previous time infertility was measured in the nation in 1992.
Not surprisingly, the older the woman, the higher the prevalence of infertility.
Yet infertility appears to be rising among younger women as well, the study finds.
In 1984, about five per cent of couples with a female partner age 18 to 29 were infertile.
By 2009-10, the prevalence for the same age group ranged from seven to 13.7 per cent.
For their analysis, researchers used data from a sample of 4,412 couples from the 2009-2010 Canadian Community Health Survey.
Infertility ranged from 11.5 per cent, to 15.7 per cent.
Those estimates are based on whether couples had reported becoming pregnant or not in the past 12 months, were not using any form of birth control within the past 12 months while having sexual intercourse, and had tried to become pregnant with their current partner. Regardless of how it was defined, each estimate represented an increase in infertility when compared with previous national estimates, said first author Tracey Bushnik, a senior analyst at Statistics Canada.
In 1992, 8.5 per cent of women age 18 to 44 who were married or living common-law were considered infertile.
In 1984, the figure was 5.4 per cent.
Not only are the emotional, physical and financial costs to couples substantial, the researchers write, but the health system also has to bear the costs of caring for premature babies or multiple births born from asssisted reproductive technology.
The new study "just confirms everything we've been gnawing on for the last little while," said Dr. Roger Pierson, a world leader in research into ovarian physiology at the University of Saskatchewan.
Canada's pregnancy specialists have been sounding an alarm over the risks of deferred motherhood. The Society of Obstetricians and Gynaecologists of Canada — which has just issued new guidelines to doctors on "advanced reproductive age" and fertility — worries that women are placing too much blind faith in high-tech fertility treatments to help them conceive once they're ready to have a baby.
For women over 40, the failure rate approaches 90 per cent.
"We're not miracle workers," said Dr. Al Yuzpe, co-author of the new study and co-founder of the Genesis Fertility Centre in Vancouver, one of the largest in-vitro-fertilization clinics in the country.
"We know that there's a precipitous drop in conception rates as women get older," he said.
The other authors of the report were: Jocelynn L. Cook, of the Department of Obstetrics and Gynecology at the University of Ottawa; Suzanne Tough, of the Departments of Pediatrics and Community Health Sciences at the University of Calgary; and John Collins, of the Department of Obstetrics and Gynecology at McMaster University in Hamilton, Ont.
In addition to the well-documented impact of age, other factors affecting female fertility include obesity, alcohol use and sexually transmitted infections.
While fewer women are smoking, more younger women are boozing heavily: reported rates of heavy drinking — defined as five or more drinks at a time at least once a month — among women age 20 to 34 increased from nine per cent in 1994, to 20 per cent in 2010.
Reported rates of chlamydia and gonorrhea are also rising, with the majority of infections reported for women under 30.
And obesity rates are climbing: In 2007-09, 21 per cent of women ages 20 to 39 in Canada were obese, up from four per cent in 1981. Obesity can interfere with a woman's normal ovarian function.
Obese men, meanwhile, have been found to have lower volumes of semen and a higher proportion of abnormal sperm. But just how much a role sperm count deterioration may be having on declining fertility is controversial.
Yuzpe said the data are not convincing.
"The question keeps coming up: Are men's sperm counts getting worse?" he said. "There might be a slight overall reduction in sperm counts, but not from 'normal' to 'abnormal' sort of thing," he said.
Yuzpe said people are much more likely today to report difficulty conceiving than they would have been in the past, "because of the stigma associated with it," but also because people didn't seek help "because there wasn't much we could do for them.
"It's only in the last 35 or 40 years that we've had anything of any significance that we could do for women, or for couples," he said.
Pierson said the study raises important individual and societal questions, including when is the right time to have a child?
"If we were to suddenly stop ART (assisted reproductive technology) and say, 'We're going to support women having children in their early 20s,' I would say that most of the infertility issue would go away.
"That's not our cultural reality," Pierson said. "We have to come to a better understanding of our biological imperatives, and our social expectations."