Hcg levels...due date of December 7??

Lauren • Mommy of 3Z's.
I thought I was due December 4th but after a U/S today I'm pushed back to the 7th. I got hcg levels done 4 days ago of 139. Today they're 748. My doc wants to repeat on 2 days due to brown discharge. Are those numbers good? Anyone else know their levels ?