There are symptoms of pain in the lower abdomen, but menstruation has not yet occurred, if you have sex during this period, without proper contraception, there is a possibility of pregnancy. During pregnancy, the uterus is enlarging and there are symptoms of pelvic congestion, there may be hidden pain in the lower abdomen, lower back pain and backache, and this symptom before the fast approaching menstruation. If pregnancy is completely ruled out, or there is no sexual intercourse after the period is clean, there is no possibility of pregnancy, and this symptom is likely to be a symptom of the pre-menstrual period. If the menstrual period is delayed for more than a week, it is best to come to the hospital, it is recommended to do ultrasound examination, blood test HCG to completely rule out the possibility of pregnancy. The uterine adnexa is normal, and the endometrium is of moderate thickness. It is recommended to take progesterone or progesterone capsules to promote the onset of menstruation.