Conventional wisdom suggests that in general, names in the English language tend to move from being considered male-gendered to female. There are some well known examples (Hillary, Clair, Leslie, etc). The graph below shows the relative gender distribution of the 100 names that have had the biggest shifts across the genders from 1880-2013. The data is normalized against the total number of people given that name, and the total number of people of each gender born that year.
Mouseover to scroll through the years, and click on a point to highlight that name.
The graphs below show the relative proportion of each of the 100 most-shifted names from 1880 to 2013. "0" shows name that was exclusively given to male babies in that year, and "1" is a name that was exclusively female. Many traditional names do trend female, and once they approach 100% female, they rarely revert. However, new names frequently appear as female, and then trend male.