Ovulation test strips are likely to be inaccurate when measured at night because they detect the level of luteinizing hormone in the urine, and once the level rises and reaches a peak, the test strips will show a strong positive result, and ovulation will occur about 24-48 hours after the strong positive result. The purpose of ovulation test is to know the time of ovulation, and then guide the coitus, will improve the chances of pregnancy. The value of luteinizing hormone in urine is highest around 10 a.m. The urine specimen should be kept around 10 a.m. in order to provide a reliable basis for ovulation.