So I was lying in bed and noticed that my tummy started pulsating. Pulsating like a heartbeat. anyone else know what this is or experienced it before?

Is this the same movement that you get in the video here https://www.youtube.com/watch?v=Vlnr81Zb9yc? If yes, it is your baby hiccuping inside your womb! It is rhythmic. They are harmless, and they are usually caused by the development of the baby’s reflexes. However, even though the hiccups are perfectly normal, you should bring them up at your next appointment because they could also be signs that your baby is not getting enough air due to cord compression. However, cord compression is extremely rare and it’s something your doctor will check for on every ultrasound you get. http://www.babymed.com/blogs/jaclyn-stewart/fetal-hiccupping-womb