Not most pregnancies in adenomyosis result in fetal arrest. Adenomyosis is the appearance of endometrial glands and mesenchyme in the myometrium, and the endometrial glands in the myometrium also bleed cyclically with the menstrual cycle, so after a period of time, the endometrial tissues of the myometrium that grow will become more and more numerous, and fibroids will be formed. If the protruding part is toward the uterine cavity, it may affect the morphology of the uterine cavity, leading to abnormal embryonic development and embryo abortion. If the uterine cavity pattern is normal, not all patients with adenomyosis will experience fetal arrest. There are many reasons for embryonic arrest, which may be caused by chromosomal abnormalities of the embryo, exposure of the pregnant woman to harmful substances, etc., and need to be considered comprehensively. It is important for patients with adenomyosis to manage their pregnancy to prevent miscarriage or other abnormalities.