Pregnancy can be detected a few days before menstruation, as early as 1 week before menstruation. However, this test requires a blood test in the hospital because this time is already 7 days before a woman’s ovulation. If the fertilized egg has already reached the uterine cavity and begun to implant, the trophoblast cells of the embryo will secrete chorionic gonadotropin, and the hormone will be manifested in the woman’s blood. If you want to test yourself, you can take a urine test 2-3 days before your period, because the concentration of hormones in urine is relatively low. To make the test accurate, it’s best to use the first urine in the morning, because the first urine in the morning is more concentrated, and the hormone level is relatively high.