Earlier studies have shown that aspirin therapy improves pregnancy rates for women undergoing IVF, while others have indicated that it increases the risk of miscarriage.
"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.
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.
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 considerable 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 risky 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.
The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research.