Pregnancy vomiting in the morning is a normal reaction, but when you vomit yellow bitter water, it is possible that your appetite was not very good last night, resulting in little or no food, and the second morning the normal pregnancy causes pregnancy vomiting, there is nothing to vomit in the intestines, so you can only vomit gastric juice. Gastric juice is strongly acidic and will burn the esophagus and throat during vomiting, making your mouth feel very uncomfortable. If you vomit even more, you will most likely vomit a small amount of gastric juice containing bile, which is a yellow, bitter liquid.