Diarrhea at 37 weeks, characterized by loose, frequent stools, is common in the late third trimester. This change in bowel habits can be unsettling when nearing your due date, often leading to questions about whether labor is beginning. While many associate this symptom with the imminent arrival of their baby, it is not a guaranteed sign of labor. Understanding the potential causes helps manage anxiety.
Diarrhea as a Sign of Impending Labor
Diarrhea late in pregnancy is linked to the body’s preparation for childbirth. This connection is driven by the release of prostaglandins, hormone-like substances that initiate labor by softening the cervix and stimulating uterine contractions.
Prostaglandins influence smooth muscle tissue, including the bowels. Their increased presence stimulates the gastrointestinal tract muscles, leading to faster transit time and looser stools. This is sometimes referred to as the body “clearing out” before delivery.
This pre-labor diarrhea may appear a few days to 48 hours before true labor contractions begin. The symptom alone is not a reliable predictor of birth timing. However, when it occurs alongside other signs like the baby dropping, increased contractions, or loss of the mucus plug, it suggests labor is approaching.
Other Common Causes in Late Pregnancy
Diarrhea in the third trimester is not always an indication of impending labor, as many non-labor factors influence gut motility. Hormonal shifts, separate from the acute prostaglandin surge, can alter the digestive system’s balance and activity. These changes may increase gut sensitivity, leading to occasional loose stools.
Dietary changes, such as increasing fiber or taking new supplements, can disrupt bowel habits. Iron supplements, commonly prescribed for anemia, are a known factor that can cause diarrhea instead of constipation. Furthermore, the stress and anxiety experienced in the final weeks of pregnancy can impact digestion due to the closely linked gut-brain axis.
Pregnant people are also susceptible to common causes like food poisoning or viral infections. Food intolerances or consuming sugar alcohols (like sorbitol or xylitol) can also trigger a temporary bout. In these cases, the diarrhea is unrelated to labor and is typically short-lived.
Managing Symptoms and Maintaining Hydration
The primary focus when experiencing diarrhea is preventing dehydration, a concern in late pregnancy. Fluid loss depletes water reserves and leads to an electrolyte imbalance. It is crucial to drink plenty of fluids, including water, clear broths, and oral rehydration solutions.
Electrolyte-containing beverages, such as sports drinks or specialized rehydration formulas, are beneficial because they replace lost sodium, potassium, and chloride. Plain water alone is insufficient to restore the mineral balance. Dietary adjustments should favor bland, easily digestible foods, such as bananas, rice, applesauce, and toast (BRAT diet components).
Temporarily avoid foods that irritate the digestive system, including high-fat, spicy, or fried foods, and those high in simple sugars. Dairy products may also be poorly tolerated, as diarrhea can cause temporary lactose intolerance. Always consult a healthcare provider before using any over-the-counter anti-diarrheal medications.
Warning Signs Requiring Medical Attention
While mild, temporary diarrhea is often benign, certain accompanying symptoms warrant immediate medical contact. Signs of severe dehydration, such as dark or infrequent urination, extreme thirst, dizziness, or a dry mouth, require prompt evaluation. Dehydration can impact the pregnant person’s well-being and potentially trigger uterine irritability.
Diarrhea accompanied by a fever of 100.4°F (38°C) or higher may indicate a bacterial or viral infection needing treatment. The presence of blood or pus in the stool, or severe abdominal pain, are concerning symptoms. Suspicion of food poisoning, particularly due to pathogens like Listeria, is serious, as some infections can pass through the placenta and affect the fetus.
Contact a healthcare provider if the diarrhea lasts longer than 48 hours without improvement or if there is a decrease in the baby’s typical movement patterns. These indicators suggest the situation requires professional assessment to rule out complications.