Freedom Ovulation Test Strips Freedom Ovulation Test Strips calculate when you are most likely to ovulate to maximise your chances of conceiving. They work by measuring the levels of luteinising hormone (LH) in the urine. LH is the hormone that stimulates the ovaries to produce & release eggs each month during the menstrual cycle, so the level of LH in the blood & urine is highest just before ovulation. Freedom Ovulation Test Strips are easy-to-read & should be used daily to maximise the chances of conceiving.