Depends partly on your age. If you are in your late thirties, forties, or fifties, it could be some rumblings of perimenapause. It's not uncommon for periods to become irregular or heavier or lighter. If it's only passed your period by four days, pregnancy might not show up yet on tests. Are you under extra stress? That could cause this too. I really think it's nothing to worry about, and you have no control over it anyway. Are you wanting to get pregnant? If so, I say just keep trying and in touch with your OBGyn. Hope this helps a little.
at 3:29 AM on Jun. 20, 2011