Fetal arrhythmia is a common abnormality during pregnancy, and its incidence is about 1 to 2%. According to this projection, about 200,000 to 400,000 pregnant women in China are found to have fetal arrhythmias during routine prenatal checkups each year, which often brings great confusion and concern to the parents-to-be. A. Diagnosis of fetal arrhythmia The normal fetal heart rhythm is regular, with a heart rate of 110-160 beats/min. Fetal arrhythmia refers to irregular fetal heart rhythm or fetal heart rate outside the normal range in the absence of contractions during routine prenatal examination. The fetal heart rate is suggested to be bradycardia in 20% of the low limit of normal heart rate and tachycardia in 20% of the high limit of normal heart rate; both of them last for more than 10 seconds. Reliable noninvasive fetal cardiac function evaluation is limited by many factors, including the small size of the fetal heart, poor display of the ventricular endocardium, difficulty in standardizing the orientation of cardiovascular structures, and poor fetal movement and maternal abdominal wall sound window. The ejection fraction (EF) and fractional shortening (FS), which are commonly used in conventional cardiac function evaluation, no longer reliably reflect the overall systolic function of the left ventricle, and the analysis of mitral valve diastolic flow velocity curve is also affected by the rapid fetal heart rate. In recent years, foreign experts have proposed the cardiovascular profile score (CVPS) system, which is a multivariate scoring method for evaluating fetal cardiac function, predicting the outcome of edematous fetuses and guiding their treatment, guiding and evaluating prenatal interventions for severe congenital cardiovascular anomalies, as well as for choosing the time frame for intrauterine treatment and evaluating the efficacy of fetal arrhythmias/heart failure. The CVPS system provides a semi-quantitative evaluation of multiple parameters related to poor fetal prognosis measured by 2D Doppler ultrasound, including fetal edema, heart/thorax area ratio, atrioventricular regurgitation, umbilical artery flow spectrum, umbilical vein and venous catheter flow spectrum, each with a score of two out of 10, i.e., a score of 10 for a fetus with normal cardiac function. If the fetus has varying degrees of variation in these five components, it is indicative of varying degrees of fetal heart failure. The CVPS is an important guide for clinical management of fetal arrhythmias/heart failure. It is generally accepted that interventions should be performed once CVPS is reduced; CVPS ≥7 points, treatment given for etiology often has good results; 7 points > CVPS ≥5 points, treatment is controversial and mostly taken to observe dynamic changes after treatment; CVPS <5 points, perinatal mortality is high, treatment is not significant or even risky, clinical interventions at this time may inhibit maternal-fetal adaptive protection and continue the mother-fetus complex to a high stress state, with unnecessary complications that threaten maternal-fetal safety. Treatment of fetal arrhythmias The treatment of fetal arrhythmias and heart failure includes: (1) maternal oral administration; (2) umbilical vein administration; (3) fetal abdominal treatment; and (4) amniotic fluid administration. Except for maternal oral drug therapy, all other methods are limited in clinical application due to their invasive nature, and there are only a few successful cases at home and abroad. At present, maternal oral drug therapy is still the preferred route of treatment, and the use of transumbilical intravenous drug therapy is only considered when the placental transit rate of the severely edematous fetus is very low, but because of the complications of umbilical vein puncture itself, such as bradycardia, which may further aggravate fetal arrhythmia and heart failure, the application of this treatment in fetal arrhythmia and heart failure is extremely limited. The use of this treatment in fetal arrhythmias and heart failure is therefore extremely limited. The choice of drugs and dose, as well as the mode of administration and frequency of treatment strategies, are developed by the fetal medicine, cardiology, and neonatology physicians together, and effective genetic counseling is provided to the pregnant woman and her family. IV. Prognosis of fetal arrhythmias Most of the fetuses with arrhythmias are with transient sinus tachycardia, isolated supraventricular preterm contractions, transient irregular rhythm, etc. These fetal arrhythmias are benign processes in the developing fetal heart and do not require emergency treatment and have a good prognosis. Only about 10% of fetal arrhythmias are persistent, rapid or slow arrhythmias with secondary damage, and irregular rhythms. Severe fetal arrhythmias are often associated with fetal heart failure and edema, and can even lead to fetal death, which can often be controlled with timely and effective management.