Ovulation tests function by detecting the reproductive hormone LH – or luteinizing hormone. Just before ovulation, women experience an “LH surge” – a brief, marked increase in the amount of luteinizing hormone in their systems. Ovulation test kits detect this sudden LH surge, allowing you to predict, with great accuracy, when you will ovulate.
A positive on an ovulation test indicates that a woman will most likely become fertile over the next 3 days – with peak fertility at 24 to 36 hours after the LH, or positive ovulation test.
Some fertility medications can however confound results. For example clomid can cause a false positive ovulation test if you begin testing too early in your cycle. Once you receive a positive result, we recommend having intercourse daily over the next 3 to 4 days.