This question is one of those that gets people to stop and think....get the paper and pencil out and really do some serious calculating. My guess would be, the facts would shock some people.
I am always discussing this subject with young parents of children under 5 (when they usually begin school) The clear and accurate answer to this question can be an enormous factor in deciding whether both parents should work out side the home, or not.....OR, one of them work part-time, or perhaps can they work opposite shifts to avoid the high cost of childcare? There is much to consider.
As a baby-boomer, no matter how I sturggle to understand that more often than not, both parents must work.....it will always go against my strong opinions on this.
Retired now, this is not one of my personal concerns.......but I have more time to preach (nag) to my kids about maybe one of them "staying home" until the kids are off to school!! lol... They listen....and then they laugh. "Mom, get out of the 60's...you gotta be kidding!!" Oh well, I try.