How early can pregnancy strip reliably be used for testing if i am pregnant.

Very sensitive: Most home urine pregnancy tests when used according to manufacturers' instructions, can detect pregnancy within 3-4 days after implantation and by 7 days of implantation in 98% of cases. When pregnancy occurs, the female body starts creating a hormone called human chorionic gonadotropin (hCG) in higher amounts during the early stages of pregnancy. That is what is detected with the urine tests.