Urine tests work in one of two ways: measuring either follicle stimulating hormone ( FSH) levels or luteinizing hormone ( LH) levels. FSH Tests: These tests do not let you know that you are ovulating; they simply measure your FSH levels to ensure that they are within normal range. If your FSH levels are not within normal range, you may have difficulty conceiving and should bring this to the immediate attention of your OB-GYN. Doctors agree that the early detection of a fertility issue may be of significant help in getting you pregnant.
LH Tests: Although your body consistently produces small amounts of LH, there is a significant surge approximately 24 hours before ovulation. This test detects levels of LH in your urine to determine whether you are about to ovulate.