I work 4 days a week, which allows me to spend one looking after my daughter. I had the option to do that, or take a (hugely) better paid job. Don't regret it for a second, and I don't think it has actually had that significant of an impact on how much I actually get done in a week.

At least until my child starts school, I wouldn't even consider working full time. Even then, I think the positive difference the extra time has made to me, and my family would make me think hard about going back to a 5 day working week.