How does a home ovulation test work and what is the LH surge?
When a woman is about to ovulate, her body releases a large amount of a hormone called LH (Luteinising Hormone). LH is always present in your urine but the levels increase (surge) in the middle of your cycle, causing you to release an egg from the ovary. This process is called ovulation. If the LH surge is present, ovulation is likely to occur in the next 24 to 36 hours. These ovulation tests detect the LH surge by measuring the amount of LH in urine.