In short yes, ovulation tests can detect pregnancy but they are meant to predict ovulation and should be used for that. The hormones that ovulation tests and pregnancy tests are looking for have different functions in the body, but their structures are very similar.  To put it simply, ovulation tests are meant to tell you when you're ovulating; they're not designed to tell you when you're pregnant. "OPKs test your urine for a surge of a hormone called luteinizing hormone (LH), which normally occurs 24-36 (hours) prior to ovulation," Dr. Thornton describes. "Some kits also measure a hormone called estrogen, which increases as an egg is growing and can help predict 'high fertility' days prior to the 'peak' or 'surge.'"