Cell phones and pregnancy

Hi ladies! Just wondering if you use your cell phone pretty often and if you consider it safe while being prego.  My husband and I only have cell phones so everyone calls us on them and we both use them alot.  This month I used 2,400 minutes!!  That's the most I've ever used, I average around 1,500 a month...don't know why it was so high this month...anyway, do you think this is fine?  My doc said she doesn't know of any problems associated with cell phones and being pregnant.  Thanks!