Having children is an example where two methodologies in happiness research dramatically diverge. One method is asking people in the moment how happy they are; the other is asking how they happy they generally feel about their lives. The first method finds that people really hate child care and is probably what you remembered.
I think the paper you're thinking of is Kahneman et al's A survey method for characterizing daily life experience: The day reconstruction method.
Notably,
In Table 1, taking care of one's children ranks just above the least enjoyable activities of working, housework, and commuting.
On the other hand, having children also harms marital satisfaction. See, for example, here.
Haven't had one of these for awhile. This thread is for questions or comments that you've felt silly about not knowing/understanding. Let's try to exchange info that seems obvious, knowing that due to the illusion of transparency it really isn't so obvious!