The First Response ovulation prediction test kit will help the patient find the time period during which she is most fertile by measuring the luteinizing hormone (LH) which is always present in the urine and which increases on the most fertile day. This increase in LH, which is called the LH surge, triggers ovulation. A simple color change in the test result indicates the surge. Most women will ovulate within 12 to 24 hours after the LH surge is detected but some may not ovulate for almost a full 2 days after the surge is detected. Usually, the patient is most fertile on the day she notices the color change from the ovulation prediction kit.
The First Response test uses a technique known as ELISA, enzyme-linked immunosorbent assay, to detect the LH surge. This is a relatively new idea in which monoclonal antibody technology is used to detect very small quantities of a protein in the urine.