Amenorrhea refers to a condition in which women don't have a period for a long time. This could be good news for most women except those trying to conceive. There are two types of amenorrhea: primary and secondary. Primary occurs when a woman has gone without having a period her whole life. Secondary is when a woman has had periods before but doesn't anymore. If you're not having a period, you're probably not ovulating, or releasing an egg ready for fertilization. This means you probably have little or no chance of becoming pregnant. You're considered to have secondary amenorrhea if you haven't had periods for six months after having regular periods. The most common cause of amenorrhea is pregnancy, so it might be a good idea to check with a doctor for more information if you're not having periods.