Natural Clearblue is the only test that detects the rise in 2 fertility hormones, estrogen & luteinising hormone (LH) before ovulation. Make love on high & peak fertality days to maximise your chances of getting pregnant naturally. Accurate The simple urine tests are proven to be over 99% accurate at detecting the LH surge. They are two times more accurate than calendar methods. Study of 101 women in the UK, comparing a simple calendar method to likelihood of conducting a test on LH surge day (2011). Tracks 2 Hormones This means its the only ovulation test that typically identifies 4 or more fertile days, more than any other ovulation test. By identifying more feritle days, you have more oppotunities to get pregnant naturally.