A Toronto research team has found a link between women who undergo fertility treatments that never resulted in pregnancy and heart problems later in life.
Dr. Jacob Udell has seen cases of women who have taken fertility drugs and then developed complications such as high blood pressure and diabetes in pregnancy.
In the medical literature, Udell said, women on fertility drugs have also been known to develop conditions resembling congestive heart failure, which left him wondering if there could be more subtle, longer-term complications.
In research published in Monday's Canadian Medical Association Journal, Udell and his colleagues looked at data on more than 28,000 women averaging age 35 who underwent fertility therapy in Ontario between 1993 and 2011. They followed the women until last March to track any cardiovascular effects such as heart attacks, stroke and heart failure.
Of these women, two-thirds never became pregnant. That fertility result was also associated with a 19 per cent relative increased risk of adverse cardiovascular events, in particular, heart failure, according to the study, titled "Failure of fertility therapy and subsequent adverse cardiovascular events."
In absolute terms, the risk was "modest," with about four additional cardiac events for every 1,000 women after 10 years of followup for those who did not deliver a child after taking fertility hormones (about 10 events), compared with those who became pregnant after fertility treatment (six events).
"Not a huge impact, and as a result not something that we would have detected anecdotally in routine clinical practice because this is not happening in such large numbers, which is reassuring," Udell, a scientist at the Institute for Clinical Evaluative Sciences (ICES) and cardiologist at the Peter Munk Cardiac Centre and Women's College Hospital, said in an interview.
The findings shouldn't dissuade women and men from trying fertility therapy, the researchers said.
Healthy lifestyle changes advocated
Rather, they're a reason for women who had unsuccessful fertility therapy years earlier to remind their family physicians.
"This is an opportunity for women to talk to their doctors about their heart health when they reach middle age. That's when the monitoring and potential modification of lifestyle patterns and or therapies may be most useful," said Udell, lead author of the study.
These lifestyle changes can include getting regular exercise, eating sensibly, not smoking, controlling blood pressure and treating high cholesterol, study co-author Dr. Donald Redelmeier, a senior scientist at ICES, said in an email.
"We don't want to alarm women who undergo fertility therapy," Redelmeier added in a release.
Udell speculates that fertility treatment may act as a "physiological stress test," similar to the treadmill stress tests cardiologists often do to get a sense of a patient's future heart risk.
The inability to conceive may help to identify some women who are high risk for eventual heart trouble, he said.
The repeated cycles women undergo during fertility treatment may also contribute to any heart issues.
One of the limitations of the study is the authors didn't know what type of drugs or doses, or the degree of monitoring received by women.
Udell said he and his colleagues plan to follow the women for a further five to 10 years. They also hope to get more information about the specific treatments women received to study the potential risks in more detail.
The Heart and Stroke Foundation of Canada and the Canada Research Chair in Medical Decision Science funded the research.