A delay of 6 days in menstruation and no pregnancy test suggest two main possibilities: first, the patient may be pregnant, but the pregnancy time is relatively short and the concentration of HCG in blood and urine is low, so it cannot be detected and needs to be monitored continuously. In general, blood test after 10 days after the patient’s last intercourse can determine pregnancy more accurately, and urine test after 13 days can determine pregnancy more accurately. If the time is too short to detect the pregnancy, it is necessary to continue to observe. Second, it should be considered a normal fluctuation of menstrual cycle. Women’s menstruation can be affected by many factors, such as emotions, diet, seasonal changes, etc., which can affect the hypothalamic-pituitary-ovarian gonadal axis of women, so women’s menstrual cycle can show small fluctuations, as long as this fluctuation is on top of their original cycle, it is normal to advance or delay within a week, there is no need to worry.