Nervous spasms. As baby's nervous system is still developing, some experts suggest that babies have completely normal spasms in theuterus as part of their development. Moving the cord. Another theory is that babies sometimes get the cord wrapped around their hand or foot and the movement is them shaking it off.I had to Google this the other day! I don't remember it happening when I was pregnant with my other two. The thought of them shaking their little foot or hand to remove the cord was cute!!!