The absence of fetal heart in the fourth month of pregnancy is usually due to embryonic arrest, which may be caused by endocrine disorders, uterine malformations, hereditary diseases and other factors. 1. endocrine disorders: if the patient suffers from diabetes, polycystic ovary syndrome, low thyroid, etc. may cause the lack of certain nutrients necessary for the growth and development of the fetus, or change the function of the ovaries, etc., resulting in four months of pregnancy after the embryo stops developing, resulting in fetal demise, and thus can not hear the fetal heart. 2. Uterine anomalies: Uterine anomalies such as unicornuate uterus, mediastinum uterus, etc., may cause the growth and development of the gestational sac to be restricted due to abnormalities in the shape of the uterine cavity, which may lead to the embryo stopping, resulting in the inability to hear the fetal heartbeat. 3. Hereditary diseases: some hereditary diseases, such as chromosomal abnormalities, may cause the fetus can not grow and develop normally, resulting in embryonic arrest and thus can not hear the fetal heart. Clinical once the patient found their own four months pregnant without fetal heartbeat, need to consult a doctor in time, improve the relevant examination, if necessary, such as induced abortion treatment.