The menstrual period has been delayed for 6 days and has not yet come, but the pregnancy test shows only one bar, for the following reasons: 1. It is possible that the amenorrhea is caused by ovulation abnormalities or endocrine disorders such as polycystic ovary syndrome; 2. Pregnancy cannot be ruled out, because if the last intercourse happened to be during ovulation and within the last week, it is possible that the situation is just conceived and the test paper cannot yet detect it. Generally if there is amenorrhea, after clean menstruation have sex without contraception, it is best to rule out the possibility of unwanted pregnancy first. If pregnancy is completely ruled out, it can be combined with ultrasound examination. If the adnexa and uterus are normal and the thickness of the endometrium is moderate, progesterone can be used to promote the onset of menstruation.