OPINION:
When our babies were very small, a group friends and I were gathered at someone's house. The conversation revolved around poop (who was doing what and how often), feeding (who was doing what and how often), and hilariously, sex (who was doing what and how often).
It may make us sound like cantankerous nags, but like most women, we also conversed about a lack of support; the wrong type of help, or at the wrong time, or performed the wrong way by our partners and husbands. It's not that we weren't grateful, but we all felt support was coming in the wrong form and at times, begrudgingly.
On that day, we decided to take matters into our own hands and hypothesised an experiment. Given none of us had a science background we were flying blind, but we wondered if we'd get more willing and unprompted support from our guys after we had sex with them.
All the literature will tell you that using sex as a bargaining chip is not a healthy way to operate a relationship. But what they don't tell you is that women and men have been manipulating the system since time began, although not always with sex.