We lowered the crib mattress over the weekend since Kaylee has learned to sit up on her own. Much to my dismay, we also had to put the bumpers back in because the first thing she did when we put her in was get her legs caught up in the bars. Even though this had never been a problem before. Go figure. She also ends up cramed into the corner while she sleeps now, even though she starts out somewhere in the middle with tons of space.