The Price of Tenure?

Thanks to PhDinHistory for pointing out a curious trend in history departments — that the proportion of tenured history professors with children has been shrinking:

According to the 2003 National Study of Postsecondary Faculty, slightly more than 50 percent of tenured history faculty did not have dependent children. Only a decade earlier, nearly three out of every four tenured history faculty had dependent children. In ten years from now, will only a quarter of tenured history faculty have dependent children?

Not surprisingly, female history professors were less likely than men to get tenure while married — “in 2003, 84 percent of tenured male history faculty were married, and only 57 of female tenured history faculty were married” — although “both male and female history faculty found it easier to obtain tenure if they did not have children,” he notes.

The $64,000 question, as he interprets it, is: Why, if you have children, are “the odds increasingly against you obtaining tenure”?

Thoughts?