How often should you have Braxton Hicks?

Question

I’m 31+1 today & I went to hospital for my weekly ultrasound. They decided to do a CTG while I was in there, which are booked to be done weekly now. 
They noticed I was having tightenings, they said they were only braxton hicks because I wasn’t feeling them. I’ve only had a little bit of a back ache. 
They said I only need to come in if I start to feel them, I have another CTG booked for Thursday.
My question is, should I really be having this many? I thought they weren’t suppose to be a consistent thing? I didn’t have them with my first, however I did have back labour, so I’m getting a little nervous now!
(Ignore babies heartbeat, I have an anterior placenta which makes it hard for them to get a consistent reading).

Answer

I had back labor with my first too and my backs been hurting at 30 weeks. I never felt BH with first or this baby knowingly. But they did tell me with first I was having contractions at 38 +6 and I don’t feel them so they sent me home. Went into labor and delivery next day because of back pain I was 7 cm. Good luck!! Following for update