New study questions recommendations suggesting women undergoing in-vitro fertilization (IVF) take a daily aspirin to boost success of the procedure. A review of 13 international studies showed that a low daily dose of aspirin had no clear effect on IVF pregnancy or birth rates, Reuters reported. The reanalyzed studies included 2,653 women undergoing IVF almost half of them took 80 to 100 milligrams of aspirin per day, and the other half were assigned to a no-aspirin "control" group. In most of the trails women started taking aspirin at the beginning of the IVF process while the duration was different in varies studies. One of the larger studies looked at 300 women that looked only at pregnancy rates did suggest a benefit. According to the results 45 percent of aspirin takers became pregnant after IVF, versus 28 percent of women not on aspirin. On the other hand, 3 of the studies compared the birth rate of 525 women who used aspirin528 who did not consume the tablet during their IVF treatment cycle. The results showed that 108 women of the first group and 119 of the other gave birth after the treatment, which had no significant difference. When the researchers combined the results of the all 13 studies, they found no overall effect on women's pregnancy or birth rates, or on their risk of miscarriage. The study was published in the Cochrane Library, belonging to the Cochrane Collaboration, an international research organization that evaluates medical evidence. In theory, aspirin could improve IVF success by boosting blood flow to the ovaries and uterus. It might also help by preventing blood clots in the vessels of the placenta, which helps nourish the baby before it's born. But studies have come to mixed conclusions. "Couples undergoing IVF often feel so desperate that they are prepared to try anything that may improve their chances of conceiving," said lead author Dr. Charalambos Siristatidis, of the University of Athens in Greece. "But given the current evidence," he added, "there is still no basis to recommend that women take aspirin to help them become pregnant."