Scientists aren’t sure of the exact causes of increased saliva during pregnancy. There is, however, evidence to suggest that increased saliva production can occur because of pregnancy-related hormone changes. Pregnancy symptoms that involve stomach acids can contribute as well. Additionally, some pregnant women may think their bodies are producing more saliva when, in fact, they are just taking more notice of it.
Fluctuations in hormones like estrogen and progesterone, for example, can cause a woman to produce more saliva while expecting a baby. The effect of hormone changes on saliva production is usually only temporary, however. Some women notice that it is worse in the first three months of pregnancy, when hormone fluctuations are most prevalent, or during the last trimester, when the growing uterus crowds other abdominal organs.
In some situations, a woman’s saliva production remains the same, but she feels as if it has increased because she is paying more attention to it. For instance, a woman who is dealing with morning sickness may spend a significant amount of time feeling nauseated and wondering whether she will vomit. This can make her more aware of the feeling of saliva in her mouth. In fact, some women even find that taking notice of the saliva’s presence makes nausea worse. Additionally, women who experience severe morning sickness, also referred to as hyperemesis gravidarum, are more likely to report excess saliva during pregnancy.
A woman may also have this issue when she avoids swallowing. Some women find that swallowing makes them feel more nauseated or may even bring on an episode of vomiting. To deal with this, some women attempt to swallow less saliva during pregnancy, which makes them feel as if they are producing excessive amounts of it. Sometimes they spit the saliva out, and though it can seem like a lot, most people produce about a quart or two (0.94 to 1.89 liters) of saliva daily, even when they are not pregnant.
Gastrointestinal changes can also cause increased production of saliva while a woman is expecting. For example, heartburn occurs when acidic contents of a person’s stomach reverse into the esophagus. The acid causes the affected person to experience a feeling of burning in her throat and chest. As a result of the acid, the body stimulates the production of more saliva and increases the saliva's bicarbonate content. Since bicarbonate is alkaline and the opposite of acidic, it helps reduce the discomfort heartburn causes.