I thought this was an interesting read. Here's an excerpt from the article.

"In 'Alone Together' (2007), a comprehensive look at the state of American marriage, the authors found that if women believe child care is unevenly divided in their homes, this imbalance is much more likely to affect their marital happiness than a perceived imbalance in, say, vacuuming.

"Or consider night duty. Sustained sleep deprivation, as we know, consigns people to their own special league of misery. But it's generally mothers, rather than fathers, who are halfway down the loonytown freeway to hysterical exhaustion, at least in the early years of parenting. According to the American Time Use Survey, women in dual-earner couples are three times more likely to report interrupted sleep if they have a child under the age of 1, and stay-at-home mothers are six times as likely to get up with their children as are stay-at-home fathers."

http://online.wsj.com/news/articles/SB10001424052702304757004579335053525792432?mod=trending_now_1

I definitely agree with the first paragraph--I know that when I felt like I was taking on the majority of childcare stuff I was not happy and let DH know he had to step it up. It was okay when I was on maternity leave but once I went back to work I needed a lot more help.