Ovulation tests measure the levels of luteinizing hormone (LH) in urine to determine when a woman is most likely to ovulate. LH is a hormone produced by the pituitary gland, and its levels increase just before ovulation. Ovulation tests can detect this LH surge, which usually happens 1-1½ days before ovulation. Some tests also measure another hormone called estrone-3-glucuronide (E3G) .

Ovulation tests are used by women who want to know when they are most fertile and increase their chances of becoming pregnant. The tests are easy to use and typically come with multiple sticks to allow for testing over several days. The user urinates on the test stick or places the stick into urine that has been collected into a sterile container, and the stick will turn a certain color or display a positive sign if an LH surge is detected. A positive result means that ovulation may soon occur, but this may not be the case for all women.

Ovulation tests can detect LH and E3G reliably about 9 times out of 10, but their accuracy depends on how well the user follows the instructions. False positive results can occur, which means the test kit may falsely predict ovulation. Ovulation tests are not perfect, and they may not be fully effective for women with polycystic ovary syndrome (PCOS) .

In summary, ovulation tests measure LH levels in urine to determine when a woman is most likely to ovulate. They are used by women who want to know when they are most fertile and increase their chances of becoming pregnant. Ovulation tests are easy to use, but their accuracy depends on how well the user follows the instructions.