Some women in early pregnancy may experience a small amount of vaginal bleeding, lower abdominal pain and other cases of preterm miscarriage, and they will choose to treat the pregnancy with birth control. Generally, if the fetus is on birth control and there is no vaginal bleeding for more than 7 days and the embryo is developing well on ultrasound, it is considered successful. The indication of successful birth control is not only the absence of vaginal bleeding, but also a combination of gynecological ultrasound, progesterone and HCG values. If there is a malformation of the uterus, there will always be bleeding during the growth and development of the embryo because the cavity of the uterus has to be enlarged, and as long as it does not affect the continued growth and development of the embryo, it can also be treated with fertility preservation. Also, if the embryo is implanted in the uterine scar, as long as it does not affect the growth and development of the embryo, a small amount of vaginal bleeding may occur in the endometrium of the scar, and as long as the embryo is healthy and developing, it is possible to continue the fertility preservation treatment. Therefore, it is not possible to determine the success of fetal preservation simply by not bleeding for a few days, this needs dynamic observation and ultrasound to determine. Under normal circumstances, if there is no bleeding for 7 days, the fetus is developing well, there is fetal heartbeat, and the development of the gestational sac matches the number of days of menopause, it is basically considered successful. In the future, we need to monitor the fetal growth and development through regular maternity checkups.