The principle of the self-test of the pregnancy test is to detect the value of HCG, the human chorionic gonadotropin. This hormone is produced by the placenta and it usually appears in the urine after a few days of pregnancy, but due to the small amount, it is not detectable by the principle of the pregnancy test at first and does not become increasingly evident until 10 to 14 days (HCG values can also be measured by blood tests and are much more accurate). Although the principle of many types of pregnancy tests indicates that a woman can do a pregnancy self-test after 1 day of missing her normal period, in reality, not all pregnant women discharge HCG hormone at the same rate and in the same amount, which varies from person to person. Experts warn that the negative reaction presented by the principle of the pregnancy test paper when the urine test is done too early may be wrong. Therefore, it is better to take a self-test with the principle of pregnancy test paper two weeks after the late arrival of the menstrual period, so that the results will be more credible. Early morning urine usually has the highest HCG value and the most accurate result will be measured with the first urine discharge from early morning. Nevertheless, if you suspect that you are pregnant, it is best to go to a maternal and child health center or hospital for an ultrasound and blood test to get an accurate conclusion! How long does it take to detect an early pregnancy test? The test can be taken 7-10 days after the event, but of course the longer it takes the more accurate it is. When the trophoblast of the fertilized egg is formed on the 6th-7th day after fertilization, it starts to secrete a small amount of HCG (human chorionic gonadotropin), after which the secretion volume increases continuously, and the serum concentration reaches its peak in the 8th-10th week of pregnancy, while the general early pregnancy test can only be detected 7-10 days after the secretion of HCG starts and the HCG reaches a certain concentration. The most important basis for a good quality early pregnancy test paper is whether it is sensitive or not, not the time. The best early pregnancy test paper test time is after the sperm-egg encounter: 24 hours + 7 + 10 = 18 days. How to read the pregnancy test paper? Some of them are made by putting urine into the small cup delivered, then sucking a few drops into the drop window with a straw, and waiting for a few minutes to see a red line appear in the display window, one is not pregnant and two are pregnant. There are also some that are connected to the cup, the lower end of the test strip into the urine, a while later you can see the liquid on the seep, showing red lines, again one is not, two are. In order to improve the accuracy, on the one hand, it depends on the quality of the test strips themselves, the ones bought in pharmacies usually have no problems; on the other hand, when testing, use the morning urine, and also, when dropping the liquid, be careful not to contaminate the display window, affecting the accuracy. If it is a direct immersion type test strip, be careful not to let the urine in the cup diffuse over the warning line on the test strip, if it exceeds, it will also affect the results. If you are worried about the inaccuracy of the result, you can recheck it every three to five days. What should I pay attention to when using pregnancy test strips? Be sure to pay attention to the date of manufacture on the box when using them and do not use expired test cards because the chemicals will become ineffective over time. If you are not sure about the test result, it is better to call the consultation number and ask your doctor to complete the test under his or her guidance. For example, if you drink too much water and your urine is diluted, your doctor will tell you if you need to retest again. If the test is positive but very inconspicuous, you should assume that you are pregnant and go to the hospital for a check-up.