21 weeks pregnant chest tightness dyspnea may be normal, but does not rule out pathological factors such as heart disease, lung infection, etc., can be relieved by rest, symptomatic treatment and other methods. 1. Normal situation: 21 weeks of pregnancy belongs to the middle of pregnancy, the uterus increases, the diaphragm uplifts, the volume of the chest cavity becomes smaller, the lung expansion is affected, which may lead to pregnant women to appear 21 weeks of pregnancy chest tightness, dyspnea. At this time, pregnant women can rest and improve sleep, the symptoms can usually be relieved. 2. Heart disease: If a pregnant woman has congenital heart disease, with the increase of pregnancy, the pregnant woman’s blood volume increases, the heart burden increases, may appear 21 weeks pregnant chest tightness, dyspnea. At this time, pregnant women should ensure adequate rest, avoid overwork and emotional excitement, if the infection is induced, should promptly follow the doctor’s instructions to use antibiotics and other drugs, such as amoxicillin and other treatment of infection. 3. Lung infections: As the resistance of pregnant women decreases during pregnancy, they are prone to lung infections, leading to a decrease in the function of air exchange in the lungs, and chest tightness and dyspnea in 21 weeks of pregnancy. At this time, if it is clear that it is a bacterial infection, antibiotics such as cefixime can be used for treatment. Note that the above drugs should be used under the guidance of a doctor, avoid unauthorized use of drugs to avoid adverse effects. If a pregnant woman has chest tightness and dyspnea at 21 weeks of pregnancy, it is recommended to consult a doctor in time, complete the relevant examinations, clarify the cause of the disease, and treat the symptoms.