As with many medical studies the results of studies on men and women and low dose aspirin are confusing and sometimes contradictory but remember that the newest studies published in peer-reviewed journals such as the NEJM or The Lancet, Nature, and Science, are built on the information obtained from the earlier studies and are therefore likely to be correct even when they contradict the older studies.
Studies of the results for women and girls are especially important because until recently most studies were conducted on men and only in recent years has it been shown that the results for women can vary greatly from those for men. That one chromosome is very important.
A randomized trial published in the NEJM in 2005 found only a tiny, 9% improvement in preventing initial heart attacks in women so the new studies should be considered especially important for women when considering the proven risks vs the small potential benefits of low dose aspirin therapy.
Quoted from NEJM: