The main cause of fetal heart irregularity is intrauterine hypoxia, in addition, some maternal diseases, drugs, etc. can also cause fetal heart irregularity. 1. Intrauterine hypoxia: it is mostly seen in abnormalities of the placenta and umbilical cord, such as umbilical cord around the neck, placental abruption, decreased function of the placenta, etc., which can trigger intrauterine hypoxia, resulting in abnormal fetal heart. In addition, the abnormal amount of amniotic fluid can also cause abnormal fetal heart. 2. Maternal diseases: such as gestational hypertension, gestational diabetes mellitus, etc., can make the placental blood vessel narrowing, spasm and other abnormalities, so that the blood supply of the fetus is reduced, thus triggering the fetal heart abnormalities, or the mother suffers from heart failure, pulmonary insufficiency and other diseases, their own blood oxygen level is low, can also affect the fetus, triggering fetal heart abnormalities. 3. Drug factors: such as the use of excessive sedative drugs, anesthesia drugs, or improper use of contraction drugs, etc., can affect the fetal heart rate. When the fetal heart rate is abnormal, pregnant women should consult a doctor in time to find out the cause of the disease under the guidance of the doctor, and if necessary, carry out appropriate treatment.