Preparation for pregnancy during the menstrual period out of a little blood and then no longer may be the first sign of miscarriage, ectopic pregnancy, dysfunctional uterine bleeding and other causes. 1. Pre-eclampsia: When menstrual abnormalities occur during preparation for pregnancy, the first thing to do is to rule out pregnancy. You can go to the hospital to draw blood to check HCG, if HCG is elevated consider pregnancy. Vaginal bleeding after pregnancy, may be the first sign of miscarriage, the patient should pay attention to bed rest, if necessary, under the guidance of the doctor for fetal preservation treatment. 2. Ectopic pregnancy: after identifying pregnancy, ectopic pregnancy cannot be ruled out. At this time, the pregnancy is still short, may not be able to see the gestational sac in the uterus, can be one week after the ultrasound, if the gestational sac is seen outside the uterine cavity, considering ectopic pregnancy, need to be dealt with in a timely manner. 3. Dysfunctional uterine bleeding: If the blood test for HCG is negative, it is considered abnormal menstruation. You can take a sex hormone test and adjust menstruation under the guidance of your doctor. If you have abnormal menstruation during the preparation for pregnancy, you need to consult a doctor in time to clarify the cause of the disease and target treatment.