It’s fairly unusual to be pregnant and still have a normal period. This is because the very thing that causes women to menstruate is the drop in progesterone that occurs only if fertilization does not happen. If a woman were pregnant, her progesterone levels would remain high, thus preventing her from having a period. Of course, there are times when pregnant women do indeed bleed, but by definition, these bleeding episodes are not true menstrual periods:

1. Implantation spotting: This is usually brownish spotting that occurs in some women about a week or two following fertilization. It is due to the egg implanting in the uterine lining, causing a small amount of the lining to be shed.
2. Bleeding due to hormonal shifts occurring with pregnancy: In this case, it may be perfectly normal, or it may signal a potential problem requiring a physician’s observation.

Then there are the cases where the opposite occurs, in which a woman actually thinks she is pregnant when she really is not. The most common cause of this is when women have a delayed ovulation, which causes them to menstruate later than usual, often leading them to think that they are pregnant because their period is late.

Regardless the easiest way to determine why you are or are not bleeding is to chart your waking temperature. Once you do so, you will probably find that it provides so much valuable information that you’ll wonder how you got by while being so unaware.