19Ability to Sleep
The first trimester offers waves of exhaustion that hit so hard mom will gladly sleep wherever and whenever she gets the chance. In fact, she actually can still sleep because she hasn't gained enough weight to be totally uncomfortable.
It's likely mom will still be tired during the third trimester, but
trying to sleep is a bit tricky by that point. Mom will likely have been told that sleeping on her back is off limits, and she obviously can't sleep on her stomach. Even if she does find a comfortable position, the constant kicking and needing to pee will interrupt her rest or make it impossible for her to drift off to dreams.