The time for bleeding from a fertilized egg is usually about one week after the formation of the egg. During this time period, the fertilized egg has just arrived in the uterine cavity and started to settle. If the ovaries do not produce sufficient levels of estrogen and progesterone, this can lead to a small amount of exfoliation of the endometrium causing breakthrough bleeding. Strictly speaking, this is an abnormal manifestation. Most patients present with only a small amount of light pink or coffee colored bloody discharge that lasts for about 3-5 days. This bleeding will naturally stop if the level of progesterone produced by the ovaries begins to rise and the fertilized egg is able to complete the process of implantation. If the fertilization process fails due to a persistent deficiency in the level of progesterone secreted by the ovaries, or due to various harmful factors such as viral infection, drug damage, radioactive damage, tobacco and alcohol stimulation during fertilization, the menstrual flow will be observed.