I like to wait for them to age up naturally - they are boring yes, but they are a challenge too. They eat, sleep, poop, need attention and cry for all of the above which is actually how it is in real life. So for the short time that they are babies, life revolves around them and their needs. Sims don't get enough sleep, don't get enough time for fun or skilling or anything else. So when they grow up it's a relief and a small victory that they were not taken away. When I'm not in the mood for them though I go play another house for a few days.
