The 13th day of ovulation is equivalent to the 27th day of the menstrual cycle, and the appearance of brown discharge is considered to be an early pregnancy with preeclampsia, and blood HCG and progesterone tests should be done. If the blood HCG exceeds the normal value range, suggesting early pregnancy, if the value of progesterone is low, suggesting that the luteal function is insufficient, you can supplement the progesterone preparation, every other day blood test HCG, if the value is doubled, suggesting that the embryo is well developed, or suggesting that the embryo is developing abnormally, if the value of progesterone is obviously low, and can not be ruled out ectopic pregnancy, you need to actively observe the changes. If you exclude early pregnancy, consider the performance of menstruation, most women will have a small amount of brown discharge before menstruation, it is normal, if the brown discharge occurs after coitus, and vaginitis, cervicitis, cervical lesions related, it is best to do gynecological examination, timely treatment, so as not to delay the condition.