Rotational Play - Keeping the population in check!

When I play rotationally I don't tend to limit the amount of children my Sims have unless it fits their storyline. I typically am only playing 6-8 families at a time when playing rotationally and I choose the amount of kids they have based on the story I've made up for them. I have many of the kids marry my other rotational families so that kind of keeps the number of Sims in check to a certain point.