If the test is still white on the thirteenth day of ovulation, it does not mean that you are not pregnant. It is recommended to test again after 5 days to find out if you are pregnant. After ovulation, if the sperm and egg unite on the day of sex to form a fertilized egg, it takes an average of 9-13 days for the fertilized egg to enter the uterine cavity. After entering the uterine cavity, the fertilized egg does not settle immediately, but has to be free for 2-3 days before it settles. Only after the fertilized egg settles, the trophoblast cells start to secrete blood HCG, so if the test is done on the 13th day of ovulation, it is possible that the fertilized egg has not yet settled, so the test is a blank slate. It is recommended to test again 5 days or 1 week apart using the early pregnancy test.