The LH surge refers to a rapid increase in the hormone luteinizing hormone (LH) that occurs in the menstrual cycle. This surge typically happens around the middle of the cycle, signaling the body to prepare for ovulation. It is a crucial part of the reproductive process, as it triggers the release of an egg from the ovary. Monitoring the LH surge can be important for those trying to conceive, as it indicates the most fertile days. Many women use ovulation predictor kits to detect this surge, which helps them identify their peak fertility window for potential pregnancy.