how can I tell my parents?

Okay, well I am at uni at the moment – just started my first year doing a media degree. And don’t get me wrong it’s good, I enjoy parts of it and the staff and students are all pleasant enough. I just don’t feel like it’s what I want; I don’t feel any real drive to get the work done and to turn up to the lectures.
For the last 4 years I’ve been going back and forth between media and midwifery, I know completely different.
But right now, midwifery has this massive appeal to me and I am willing to go back to school for the year and get the qualifications I need and such – problem is I don’t know how to tell my parents. I have changed my mind and switched courses so many times over the last 4 years, and they have always been so supportive – and right now they think I am happy and settled at uni, how can I tell them that I want to change?