If the dad is the stay-at-home parent, than the Census Bureau considers it to be child-care, versus if it was the mom at home:
“It’s not baby-sitting when Daddy does it.”
It’s been seven years, but I’ve never forgotten those words. My neighbor across the street was heading out for work, tall, well-dressed and ready. Her child, a few years older than mine, had just wailed, “But I don’t want Daddy to baby-sit!” She squashed that plaint like a bug, and five minutes later (I was pushing my son on the swing in their front yard) I saw her car head down the driveway.
It’s not baby-sitting when Daddy does it. Who wouldn’t agree with that? The U.S. Census Bureau, apparently. When both parents are present in the household, the Census Bureau assumes for the purposes of its “Who’s Minding the Kids?” report, that the mother is the “designated parent.” And when the designated parent is working or at school, the bureau would like to know who’s providing child care.
If the answer is Daddy, as it was 26 percent of the time when these numbers were last released, in 2005, and 32 percent of the time in 2010, the Census Bureau calls that “care.” But if Mom is caring for a child while Dad’s at work, that’s not a “child care arrangement,” but something else. Parenting, presumably.
You can read the rest of the NY Times article at: http://parenting.blogs.nytimes.com/2012/02/08/the-census-bureau-counts-fathers-as-child-care/ 
Do you think that the gender norm is ever going to change that mom is the designated parent?