I asked the same question a couple of weeks ago but didn't get any responses. My post partum bleeding stopped at 4 weeks completely and returned a day before I reached 6 weeks, I asked the doctor at my six week check and she said it was probably a period. That's what I thought anyway because I had all the usual symptoms such as headache, lower back pain and cramp. Do you have any of your usual symptoms of a period? It probably is that anyway, especially if your post partum bleeding stopped for a good while before you bled again. Keep an eye on the bleeding, if it tails off it's probably a period. It is possible though according to my doc anyway. It came as a shock to me because mine never returned with my first until she was six months and this time six weeks, I suppose every post partum recovery is different xx