Pregnancy alone does not usually cause phlegm. If phlegm occurs during pregnancy, it may be due to poor physical condition, improper diet, excessive secretion of gastric acid or respiratory tract infection. 1. Poor physical condition of pregnant women: There are physical differences between different pregnant women, and some pregnant women with poor physical condition will experience phlegm. Poor physical condition of pregnant women’s body immunity is lower, easily affected by the external environment and infected with bacteria, which will lead to phlegm symptoms. 2. Improper diet: If a pregnant woman eats too much greasy and sweet food during pregnancy, it is easy to stimulate the pharynx to make the secretion thicker and more phlegm. It is recommended that pregnant women do not eat too sweet, too spicy and too greasy food, and drink more boiled water. 3. Excessive secretion of gastric acid: the increase of progesterone in pregnant women during pregnancy stimulates gastrointestinal peristalsis, leading to increased secretion of gastric acid. Some pregnant women may experience acid reflux that stimulates the throat, inducing inflammation of the throat and increasing secretions. 4. Respiratory infections: phlegm during pregnancy may also be a respiratory infection, such as colds, chronic pharyngitis, rhinitis and so on. Pregnant women who have phlegm, it is recommended to go to the hospital in a timely manner to check the cause of the disease and follow the doctor’s instructions to deal with the treatment, do not blindly take their own medicine.