How soon can a pregnancy test stick detect pregnancy?

In general, pregnancy test sticks can detect pregnancy about a week after the expected start of the menstrual cycle. This is because after pregnancy, the female body begins to produce a hormone called human chorionic gonadotropin (hCG), and pregnancy test sticks determine pregnancy by detecting hCG levels in urine. However, the sensitivity varies among different brands of pregnancy test sticks, and some can detect hCG a few days before the expected menstrual cycle. For more accurate results, it is recommended to wait until a week after missing the menstrual period before performing the test.

1. If the menstrual cycle is regular, a pregnancy test can be performed about 35 days after the onset of the last menstrual period (i.e., 7-10 days after amenorrhea). At this time, if pregnant, the hCG levels in the urine are usually high enough to be accurately detected by the pregnancy test stick.

2. If the timing of sexual intercourse is clearly known, a pregnancy test can be performed about 14 days after intercourse. This is because after intercourse during the ovulation period, the fertilized egg requires a certain amount of time to complete the fertilization process and implant. Only after implantation do the trophoblast cells begin to secrete hCG. Usually around 14 days after intercourse, the hCG levels in the urine are already high enough to be detected by the pregnancy test stick.

To improve the accuracy of the test, it is recommended to use first morning urine, as it is more concentrated and has a relatively higher hCG concentration. If the test result is negative but there is still doubt, it is recommended to repeat the test after 7-10 days or visit a hospital for a comprehensive examination to confirm whether or not pregnancy has occurred.