Ovulation Test (LH self Test) 10 units. For women who need to know your most fertile time is a good method that may hasten the moment so desired pregnancy. These tests detect high reliability with the increase in luteinizing hormone (LH) in urine, this increase in LH before ovulation is that only lasted 24-48 hours. This increase in LH occurs approximately 13 to 14 of the cycle, 24 to 36 hours before ovulation are easily detectable in the urine.