Ovulation test strips are used to detect and infer the time of ovulation, mainly to detect the level of luteinizing hormone (LH) in the body, and whether or not you are pregnant depends on the level of human chorionic gonadotropin (hCG) in the body, the reason why there is a mysterious connection between these two seemingly unrelated things is that these two molecules contain the same structure, both can make the test strip change color, so the use of ovulation test strips to detect There is some scientific basis for using ovulation test strips to detect pregnancy. However, because their remaining structures are different, their functions and secretion characteristics are also different, so the results of pregnancy tests with ovulation test paper also need to pay attention to some issues. When the ovulation test paper is positive, it generally indicates that ovulation is imminent. After ovulation, the sperm-egg union forms a fertilized egg, and the fertilized egg is planted to the endometrium from the fallopian tube to the uterus before the embryo starts to secrete hCG. When the embryo first stretches out its tentacles and invades the endometrium, it starts to secrete hCG to the bloodstream at the earliest on the 10th day after ovulation, that is, when the pregnancy is nearly 4 weeks old, which can be measured from the serum and is the diagnosis of The earliest time to diagnose pregnancy is 10 days after ovulation, that is, nearly 4 weeks after pregnancy. Therefore, most of the positives detected by ovulation test paper before that time may be luteinizing hormone (LH), which has not been completely metabolized, rather than hCG. There is another special case, as mentioned before, which is most common in patients with polycystic ovary syndrome, where LH remains high for a long time due to non-ovulation, and the ovulation test paper is always positive as shown in the figure below. In this case, the pregnancy test will be inaccurate. Another situation is that during ovulation promotion or ovulation monitoring, in order to make the follicles expel smoothly, the doctor may give an injection, commonly known as “egg breakers”, which is actually hCG. However, the level of metabolism of the drug varies from person to person, and generally speaking, it takes 5-7 days for the drug to be completely metabolized in the body, and the test results at this time can basically exclude the interference of the drug. Therefore, given that there are so many influencing factors, it is still not recommended to use ovulation test strips for pregnancy testing.