The symptoms of chest tightness and breathlessness in pregnant women in more than five months of pregnancy may be caused by normal pregnancy reaction and hormone level changes, but we can’t rule out pathological factors such as heart disease. 1. Normal pregnancy reaction: due to the gradual growth of the fetus, the uterus upward compression, diaphragm uplift, some pregnant women will have chest tightness, this is a normal reaction to pregnancy, can be adjusted through the depth and frequency of respiration or to change the position of relief. 2. Hormone level changes: Due to the increased secretion of progesterone during pregnancy, the peristalsis of the gastrointestinal tract of pregnant women slows down and the gastrointestinal tract is prone to flatulence, which may lead to the above reaction. 3. Heart disease: If a pregnant woman suffers from heart disease before pregnancy, due to the increase in blood volume during pregnancy, increasing the burden on the heart, there may be chest tightness in more than five months of pregnancy, unable to breathe. If the above situation occurs, affecting the daily life of pregnant women, it is recommended to consult a doctor in time, under the guidance of the doctor, improve the relevant examination, to clarify the cause of the disease, symptomatic treatment.