The use of ovulation test paper has been monitoring is negative, the patient may also be pregnant, this is mainly because of the following two aspects of the reason: First, ovulation test paper test results by the quality of the patient’s test paper, the concentration of the patient’s urine as well as the patient’s test process is correct, and many other factors, the results of the test may not be accurate, the ovulation test paper has been negative patients may also be able to ovulation, and the patient may also be ovulated. The patient also has the possibility of fertilization. Second, the patient has been monitoring the ovulation test paper is negative, proving that the patient in the process of monitoring the possibility of ovulation did not occur, but after the female coitus, sperm can survive in the female body for 72 hours, if the patient after ovulation within 3 days of ovulation, the possibility of female fertilization, the patient in the coitus also need to continue to monitor.