A woman may be pregnant if she does not have a period because she will not have a period when she is pregnant. It is recommended that a woman use a pregnancy test to test her urine and if the result is positive, she may be pregnant. If the result is positive, it means that she may be pregnant. If a woman does not have a period and pregnancy is ruled out, there may be other reasons. For example, taking birth control pills can cause endocrine imbalance, which can also lead to a lack of menstruation. Cervical adhesions caused by uterine surgery can also cause menstrual blood to be retained and prevent menstruation. There are also other reasons why women do not menstruate, such as excessive stress, environmental changes, and irrational diets that can affect endocrine imbalance, which may lead to delayed menstruation or even no menstruation.