It depended on where you lived, but overall the chances were incredibly low. First off, in the medieval period, the full ideas of maleficium (the use of magic for evil purposes) had not been developed. It was through the course of the sixteenth and early seventeenth centuries that ideas about what constituted a witch, the devil's sabbat, and the what evil uses of magic looked like.

Closer to your question is the question how many women overall were accused of witchcraft. The number is unknowable, but based on information from England and Germany, perhaps as many as 50,000 people were executed for witchcraft. Since about 85-90% of those accused were women, we can say that about 42,500-45,000 women were executed for witchcraft. If we give an estimated execution rate of 50% (the approximate rate for Germany, where about half the executions took place), then perhaps as many as 90,000 women were formally accused of witchcraft between 1450-1750.

While that number may seem enormous, recall that that represents a tiny fraction of the number of women that lived in Early Modern Europe during that time. In 1600, Holland's population was 1.5 million, England's was over 4 million, and France was almost five times that. Estimating half of those populations were women gives us at least 12 million women in just three kingdoms/nations. Germany, Spain, Italy, etc. had millions more to add, making any formal accusation of witchcraft rather unlikely.

However, this is just a rough population average over a huge area. Older women were more likely to be accused than younger women; people with families or living relatives were less likely to be accused than social outcasts or feeble elders. If you were a post-menopausal woman living in East Anglia in 1645, or Bavaria in the 1590s, the likelihood of accusations skyrockets. This does not mean that there would be a certainty, just that the odds would increase from zero to perhaps 1 or 2 in 100.

Witchcraft accusations usually arose in situations where the normal order or method of dealing with conflict had broken down. That was why England saw its greatest hunts during the Civil War. For the Holy Roman Empire, areas experiencing turbulence in religion, disease and famine made for fertile grounds for witchcraft accusations. Overall, any given female was more likely to die in childbirth, or as a girl under age 10 than as a result of witchcraft and its accusations.

Sources: Lyndal Roper, Witch Craze; Gaskill, Witchcraft; A Very Short Introduction; Wrigley, "Urban Growth and Agricultural Change; England and the Continent in the Early Modern Period" Journal of Interdisciplinary History 1985.