After pregnancy, women will have different reactions due to various changes in their body. An increase in heart rate is a common reaction, which may be caused by the following reasons: firstly, the heart load is heavier than usual, and an increase in heart rate can increase the ejection volume of the heart, which is a compensatory reaction. The second is rapid heartbeat caused by excessive mental tension and physical exertion. It is recommended to pay attention to rest and not to be too excited and nervous. The third one is anemia. Many pregnant women may become anemic after 12 weeks, and the increase of heart rate is caused by the increase of oxygen uptake in the body. The fourth, usually seen around 35 weeks, is that the overall cardiac load of pregnant women is the greatest at this stage, which may also cause an increase in heart rate. The fifth, organic cardiac pathology, is heart disease caused by hypertension during pregnancy, in which case prompt medical attention is required.