There is a possibility of overlap between implantation bleeding and menstrual periods, with implantation bleeding occurring around day 7 after the formation of the fertilized egg, when it reaches the uterine cavity and begins to settle. If the ovaries produce low levels of estrogen and progesterone levels have not yet risen, this can lead to a small amount of endometrial stripping bleeding, known as implantation bleeding. The implantation bleeding lasts for about 3-5 days, after which the corpus luteum of the ovary begins to secrete more progesterone, which restores the exfoliated endometrium and stops the bleeding. However, during the process of fertilized egg implantation, if you are infected with a specific virus or take medication that affects the development of the embryo, or receive radioactive damage, it is possible that the implantation of the fertilized egg will fail. Once the fertilized egg fails to implant, the ovarian corpus luteum will atrophy rapidly and progesterone levels will drop rapidly, leading to endometrial stripping and bleeding to form menstruation, a condition that can result in ovulatory bleeding overlapping with menstruation.