I am roughly 5 5 wk pregnany and just today started bleeding brown blood it s heavier than spotting but lighter than a period I have no cramping should I be concerned about a miscarriage?

Common. I tell patients that any bleeding in pregnancy is not normal, but common. You should let your OB know if it becomes heavier or if there is any associated pain or cramps. Many pregnant patients spot or have dark blood and continue to have normal healthy babies. Check with your OB & best of luck to you. An ultrasound would be reassuring.