Since the late 80’s, a lot of other fields have open up to women. Business is not nearly as much of a old boy’s club, as it was in the past.
Perhaps with more options available, programming doesn’t seem as appealing. For example, engineering has improved since the early 1980s, when only 5.8% of engineers in the U.S. were women. It’s still low, with only 14% of engineers being women, but much higher than it’s been in the past.
That is a lot of engineers, that in the past may have felt limited to programming.