The duration of a false positive pregnancy test before menstruation is usually undetermined and is mainly related to the changes in the hormone levels in the body of the test taker and cannot be generalized. First of all, it should be clear that not all women will have a false positive before menstruation. If you are not sure whether you are really pregnant or not, or if you find a weak positive test in your morning urine with a morning pregnancy test, it is advisable to go to the hospital to have a blood test to determine whether you are pregnant or not. During this period, women should be very cautious and avoid taking any medication that may cause abnormal development of the fetus. If pregnancy is clearly diagnosed after the test, it is important to ensure adequate intake of nutrients and to eat foods high in protein and vitamins. In addition, if there is a history of previous miscarriage, when there is a false positive pregnancy test, you should also consider whether you have had another miscarriage and need to actively treat it before considering pregnancy. If there is no history of miscarriage and no other uncomfortable symptoms, most of them are normal and there is no need to worry too much.