Additional time off because of no back up babysitter ?

One of six administrative assistants in my office is about to have a baby, and has announced that she will need any vacation week off that her daycare is closed (which apparently is Christmas, Thanksgiving week, all school vacation weeks, etc.). She is married, but her husband travels for work , and neither have family in the area.

I know the old adage that employees will be treated fairly, but not necessarily equally, but frankly, while she certainly deserves a vacation, I feel it's unfair to burden the rest of the staff for multiple weeks, just because she doesn't have a back up babysitter. (and what kind of daycare is closed that much?! :)

Is this 'fair' ?