Heartburn in Pregnancy Why does it happen? Heartburn is incredibly common and will plague between 17%-45% of pregnant people (Vazquez JC. Heartburn in pregnancy. BMJ Clin Evid. 2015;2015:1411. Published 2015 Sep 8.). This happen because of two hormones: progesterone and relaxin. They are responsible for relaxing the muscles in your body during pregnancy to allow for growth and stretching in order to accommodate your baby. This causes your esophagus and the sphincter that keeps it closed to relax as well. Also, as your baby grows your “real estate” gets smaller and smaller. With this change, your stomach gets squished which forces stomach acid back up into your esophagus. Not pleasant, but there are ways to combat this physical change and discomfort! First, what not to do! - Do not stop eating. Your baby needs to be nourished. Not eating will actually increase your stomach acid making your heartburn worse. - Do not munch on antacids (TUMS, Rolaids) like candy as this has been linked to...