My monthly cycle is about 20 days late. Does this mean I'm pregnant or can there be another reason?

Several reason. There could be several reasons why a woman may be late for their menstrual cycle. One certainly could be pregnancy and taking a home pregnancy test is a good first step. Other factors, such as emotional or physical stress can also cause a women to miss or be late for a menstrual cycle. If this continues and you are not pregnant, it should be evaluated by your doctor.