A red line on the pregnancy test stick generally suggests that not enough HCG has been detected, and the reasons for this may be that the test time is too early, there is no pregnancy, and improper operation. 1. Test too early: about 10 days after the wrong menstrual period, the pregnancy test stick test whether pregnancy is accurate, if the test time is too early, the concentration of human chorionic gonadotropin in the urine is too low, the pregnancy test stick can not test, so the pregnancy test stick can not appear positive. 2. Rule out pregnancy: more than 10 days after the wrong period, the pregnancy test is still a bar, generally can rule out the possibility of pregnancy. It is best to go to the hospital to take a blood test for HCG to rule out pregnancy and then promptly adjust the menstrual cycle. 3. Improper operation: In the test, if the operation is improper, or the pregnancy test expired, etc. may lead to invalid pregnancy test. If the menstrual delay pregnancy test stick a line or suspected pregnancy, need to go to the hospital in time, under the guidance of the doctor for standardized testing.