A strong positive test on ovulation test paper usually turns weak in about 24 to 48 hours, but there will be individual differences. Women who are preparing for pregnancy can monitor ovulation through ovulation test strips under the guidance of a doctor. You can start monitoring from the 10th day of the menstrual cycle, as the luteinizing hormone level in the urine before ovulation will reach its peak value, at this time, the ovulation test paper will be strong positive, so generally the ovulation test paper will be strong positive about 24~48 hours after the ovulation test paper will be ovulated, the test paper will also turn weak positive, but there will be individual differences. It is recommended to use ovulation test paper at the same time period to minimize monitoring errors. When the ovulation test paper is strongly positive, you can reasonably arrange coitus under the guidance of the doctor. However, since ovulation test paper may be affected by a variety of factors, and false-positive results may occur, the results are not completely reliable, and ultrasound can be chosen to monitor follicular development to guide coitus to improve the chances of conception. Consult your physician for more information.