I've had a couple of experiences with brown discharge. The first was brown sludge - the best way I can describe it. This started at around 4 weeks pregnant and went on for 2 weeks. I didn't have any red bleeding or pain but it was a miscarriage.

The second one was brown spotting at around 5 weeks and then again at 6 weeks. Both times my doc put me on bed rest (I had a history of m/c by then) and all continued on well until Brock was born.

Generally brown is OK but red is more reason for concern.