The constant production of acid inside the mouth may be caused by a woman’s early pregnancy reaction due to pregnancy. The acidity usually continues over time until about 12 weeks of pregnancy and does not require special treatment. If a woman who has a regular menstrual cycle does not have a period for 10-20 days, it is highly likely that she is pregnant. A pregnancy test combined with nausea, vomiting and other early pregnancy reactions, a urine or blood HCG test and an ultrasound will confirm the pregnancy and the state of pregnancy.