Having loose stools is pretty common during pregnancy. When it lasts up to a few days, it’s usually not directly due to pregnancy itself. Common culprits include eating certain foods (like artificial sweeteners) or having food intolerances (like to lactose or fructose). Otherwise, the most common cause of diarrhea is infection with a bacteria or virus—aka the stomach flu (caused by rotavirus and norovirus) or food poisoning (from eating contaminated food). If you have true diarrhea that continues for more than a day, talk to your doctor to ensure you’re getting enough fluids.
Keep in mind that if you have inflammatory bowel disease and Crohn’s disease, symptoms like diarrhea tend to worsen during pregnancy. And later in pregnancy, diarrhea may be a sign of labor. If you have diarrhea with lower back pain and increased vaginal discharge, call your doctor to rule out preterm birth.