Not necessarily. There could be a lot of reasons for a heavier than normal period.

What could they be?

Stress is one of them, hormonal shifts, and probably a bunch of others that I don't know off the top of my head.

I started having at least one incredibly heavy period every year since I started menstruating. I would have unbelievable cramps that left me in bed with a heating pad scalding my abdomen for days at a time, and a horrible flow that left me exhausted and pale, for at least a week, sometimes longer. I have even passed clots. I know they weren't miscarriages since I have been having periods like this since I was 12, I wasn't sexually active until I was 21.

Hope this helps. I know I don't have many answers but it's happened to me a lot so don't worry too much.

A heavier period that is late is most likely not a miscarriage. It is possible, but would be more the exception than the rule. Even if your cycle has always been the same, it can change for no apparent reason. Before I had my son, I had 3 day periods that were super light. After I stopped nursing, my periods were super heavy and lasted a week. Now they are about 7 days and usually pretty light but every few months I have a super heaavy period. My cycles also used to be 28 days on the dot. Now they are between 27 & 30 days. A lot of women start having variances in their cycle at some point.

Thanks, I had heard that it was and it frightened me, I don't think I could handle it it I had another miscarriage...

Definitely this is NOT true. Sometimes periods are just late and a little heavy. This can be caused because of weight gain, stress, shifts in hormones, sometimes when you ovulate a little late it will be a later period and more stuff will come out. Sometimes people do have miscarriages and just think it's a heavy period- but I definitely think that is an exception to the rule.