I think if they have a smaller room this happen more often, due to lack of space to do certain animations. It gets worse though with every milestone because what an infant does/plans to do will ALWAYS interfere with anything the other sims want to do.
Often I have to switch to the infant and cancel anything in their que, like crawling/creeping ( last one is the most annoying one because it will not be in their que at all but they do it randomly and you can't actually cancel the action or do anything but wait it out)so it's best to always play as infant POV because else it's almost impossible to get anything done.
That all sims in the household rush to the child is also badly coded because it's totally unnecessary to make this such a priority and messes up the gameplay so much as sims quit what they're doing and come from the other side of the house to the infant/baby even if another sim is already in the area and had actions in their que as well. It's very disruptive and has been like this for years now.
I often have to lock the door to the nursery so only 1 sim can attend the baby.
