When I was pregnant, I didn't even notice monster's kicks and movements at first. I thought it was just gas. However, over time, as she got bigger and I got bigger, her movements got more and more noticeable. By the end of that summer, you could really tell when she was moving around or kicking. It was like she was trying to get out through my skin! Totally freaked me out, like a monster inside me or something. after she was born, there were days (and still are days to be honest) where she is crabby and nothing can help to calm her down. She acts like a monster, hence the nickname.