I started feeling flutters with baby at 17 weeks. I'm almost 21 weeks now and have been feeling what feels like strong muscle twitches in my uterus on and off for a week now, especially when I'm laying down. They aren't painful, but scare me every time. The main reasons I feel like they could be twitches are 1) I still occasionally feel the fluttery movements and 2) my arm or calf will randomly twitch sometimes.