The effect of sinus arrhythmia on the fetus during pregnancy should be determined by the severity of the sinus arrhythmia and whether it is accompanied by other uncomfortable symptoms. If there is no abnormality in blood pressure, abdominal ultrasound, electrocardiogram and echocardiogram, it will not affect the fetus and no special treatment is needed. If the blood pressure, abdominal ultrasound, ECG and echocardiogram are not abnormal, the fetus will not be affected and no special treatment is needed. If a pregnant woman’s sinus arrhythmia is accompanied by organic lesions, it may lead to intrauterine hypoxia and even miscarriage. If a pregnant woman has sinus arrhythmia, along with chest tightness, weakness, panic and other uncomfortable symptoms, she needs to go to the hospital in time to clearly check the specific cause of the arrhythmia, and to clarify whether the fetus is abnormal through ultrasound or other examinations, and to carry out the corresponding treatment under the guidance of the doctor to avoid aggravating the condition and affecting the growth and development of the fetus.