The few days leading up to and including the day of ovulation are the only days in each cycle when a woman can become pregnant. Unlike monitoring basal body temperature (BBT), ovulation prediction kits detect the surge of luteinizing hormone (LH test) – a key fertility hormone that rises before ovulation – to accurately identify the days before, not after, ovulation. Although ovulation test strips are widely available, in a UK study, 7 out of 10 women found the strips were not easy to use. (111 women who used and read different types of tests.)
The Clearblue ovulation test has been validated by ultrasound. A study of 40 women found 96% agreement with ovulation observed by ultrasound. Data on file. (1) Compared to not using any method.