maternity shoot worth it?

Kay
I'm really torn on whether or not to have a maternity photoshoot. I'm a first time mom and it sounds really exciting but the expense is making me question it, min I've found is £150. I'm wondering if I just leave it and then have new born pictures instead professionally done coz I figured once the baby comes im going to replace all the bump pics with the baby pics. 
I've also got a groupon route option but you only get 1 pic. How do you pic one picture from a 1-2 hour photoshoot. I suspect I might end up buying extra 3-4 which will come up to circa £75 in which case I may as well pay £150 and get over 50 pictures. 
What do you guys think?