Low-dose aspirin for in vitro fertilisation

Although it is inexpensive, easy to obtain and poses little health risk, women undergoing in vitro fertilization (IVF) cannot rely upon aspirin to help them become pregnant, according to a systematic review of nine studies.

Over-the-counter aspirin, or acetylsalicylic acid (ASA), is typically used as a pain reliever. When taken daily, aspirin might lower the risk of heart attack, clot-related strokes, and other blood flow problems. Although it has its benefits, aspirin might also cause serious side effects, such as kidney failure, bleeding problems and some kinds of strokes.

But how could it help couples conceive?

“It is thought by some that taking low-dose aspirin may improve blood flow to the uterus and therefore improve ovarian response to IVF treatment, so it may be of benefit to women who have previously responded poorly to IVF treatment,” said the review's lead author Vanessa Poustie, Ph.D., at the Institute for Child Health at the University of Liverpool in England.

Previous research on the use of aspirin with assisted conception techniques such as IVF has been inconsistent. Some studies have shown that aspirin therapy improves pregnancy rates; others have indicated that it increases the risk of miscarriage.

In the current review, Poustie and colleagues examined data from 1,449 women undergoing in vitro fertilization or intracytoplasmic sperm injection (ICSI) to treat infertility.

The studies compared the pregnancy and birth rates of women taking low-dose aspirin (150 milligrams or less taken once per day) to women taking a placebo or no treatment. Two of the studies took place in the United States; other studies were conducted in Hong Kong, Iran and Finland.

The review appears in the latest issue of The Cochrane Library , a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

According to the review results, women taking aspirin while undergoing IVF or ICSI were not significantly more likely to become pregnant than women taking a placebo or no treatment.

In addition, no significant difference in live birth rates existed between the treatment and control groups, according to the two studies that examined this outcome.

“Despite a number of high-profile studies, there still remains insufficient evidence to be able to say whether low-dose aspirin can increase the chance of women undergoing IVF having a successful pregnancy,” Poustie said.

One of the largest studies included in the review found that 45 percent of the women taking aspirin became pregnant, compared with 28 percent of the women in the control group; however, the data were not strong enough to recommend this treatment routinely to women on IVF, the reviewers said.

“Further research would need to be undertaken before we can say whether the use of low-dose aspirin has a beneficial or detrimental effect on women undergoing IVF,” Poustie said.

Although in agreement with the study authors that further research into this treatment is needed, Randall Hines, M.D., director of the division of reproductive endocrinology and infertility at the University of Mississippi Medical Center, said that a number of IVF programs already use low-dose aspirin and it would be unwise to change current practice based on the available data.

“Low-dose ASA may help some patients and does not appear to do harm,” Hines said.

In addition, Hines said that researchers at the U.S. National Institute of Child Health and Human Development, part of the National Institutes of Health, recently performed a meta-analysis that further clouds the debate over aspirin and IVF.

In the studies included in the NIH analysis, published in the October 2007 issue of the journal Fertility and Sterility, there was a “noted trend of improvement in clinical pregnancy” when women took low-dose aspirin, compared with no treatment.

Couples who want to conceive might feel desperate enough to try any course that could result in pregnancy, but it makes sense to discuss these issues with a fertility specialist, Poustie said.

“If the doctor recommends that she does not take aspirin, but the woman decides she still wishes to take it, then it is important that she informs her doctor of this. However, if she decides not to take the aspirin, she should be reassured that there is no evidence to suggest that she is reducing her chances of achieving a successful pregnancy by not taking aspirin,” Poustie said.

The review authors did not receive internal or external financial support for this analysis; however, Poustie previously took low-dose aspirin while undergoing IVF treatment.

Poustie VJ, Dodd S, Drakeley AJ. Low-dose aspirin for in vitro fertilisation. (Review). Cochrane Database of Systematic Reviews 2007, Issue 4.

The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.