Sourness in the mouth during pregnancy may be caused by early pregnancy reaction after pregnancy. The increase in hormone level in the body after pregnancy causes gastrointestinal dysfunction, reduced secretion of gastric acid and prolonged gastric emptying time, resulting in discomfort such as nausea, vomiting, heartburn and acidity in the mouth. Generally, there is no need to be nervous, you can eat soda crackers or easy-to-digest food. Most of the early pregnancy reactions disappear on their own around 12 weeks of pregnancy. After pregnancy, the uterus gradually increases in size and may exert some pressure on the stomach and intestines, resulting in indigestion and acid reflux discomfort. However, as long as the symptoms of acid reflux are not particularly obvious, you can observe for a period of time. If the symptoms are more obvious, go to the hospital for examination and take anti-acid medication under the guidance of the doctor. Also pay attention to eating less fried and high-fat food, and eat fresh vegetables, fruits and food containing coarse fiber to promote intestinal peristalsis and relieve the discomfort.