Pregnancy

Diarrhea in Pregnancy: Causes and When to Call

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Occasional diarrhea in pregnancy is usually harmless and often clears within 24 to 48 hours. Common causes include stomach bugs, food, and supplements. The main concern is dehydration, so dark urine, dizziness, a fever, blood in the stool, or diarrhea lasting more than two days are reasons to call a prenatal provider.

Last updated: July 2026

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Is diarrhea normal during pregnancy?

Diarrhea is far less common in pregnancy than constipation, and most episodes are short-lived and harmless. Loose or frequent stools now and then — often defined as three or more watery stools in a day — usually trace back to something temporary like a passing bug or a new food.

Pregnancy hormones tend to slow the gut for most people, so true diarrhea is more often about an outside cause than the pregnancy itself. Most bouts settle on their own within 24 to 48 hours with rest and fluids. The bigger question is not the diarrhea but whether it is causing dehydration, which matters more now.

What causes diarrhea when you're pregnant?

Several everyday things can loosen the stool during pregnancy. A viral or bacterial stomach bug is the most common cause, and food poisoning is a particular concern because pregnancy raises the risk from infections like listeria. Diet shifts, extra fruit and fiber, sugar substitutes, and stress can all play a role.

Prenatal supplements matter too: while iron more often causes constipation, ACOG notes that routine iron and other prenatal vitamins can change stool patterns 3. Some medications and, close to term, natural hormone shifts can bring on loose stools. Checking whether a remedy or drug is safe means reviewing medication safety in pregnancy with a clinician.

When should you worry about dehydration?

Dehydration is the main risk from diarrhea in pregnancy, because fluid needs are already higher. Warning signs include dark yellow urine, urinating far less than usual, a dry mouth, dizziness, a racing heart, or feeling faint. Diarrhea that lasts beyond 48 hours, comes with a fever above 100.4 degrees Fahrenheit, or contains blood or mucus points to an infection that may need care.

Because dehydration can also cause deep tiredness, learning how dehydration drains energy helps you catch it early. Sipping fluids steadily rather than gulping, and including some salt and simple carbohydrates, helps replace what is lost while the gut recovers.

How does diarrhea differ across pregnancy?

Timing offers clues about what is driving loose stools. Early on, hormone changes, food aversions, and a new prenatal vitamin are common triggers, and diarrhea may overlap with pregnancy nausea. A stomach bug, by contrast, can strike in any trimester and usually brings cramping and other symptoms.

Loose stools around a period or during perimenopause, driven by prostaglandins, are a familiar pattern, and something similar can appear in the final days before labor as the body prepares. In the third trimester, dehydration is worth taking seriously quickly, since it can trigger contractions.

When diarrhea in pregnancy needs a clinician

Most diarrhea passes, but some situations call for prompt review rather than waiting it out. Signs of dehydration, diarrhea lasting more than 48 hours, blood or mucus in the stool, a fever, or severe or constant abdominal pain are reasons to contact a prenatal provider the same day. NICE antenatal guidance recommends seeking advice when symptoms are severe, persistent, or come with feeling generally unwell 2.

In the third trimester, reduced fetal movement or regular cramping alongside diarrhea deserves urgent attention. Bringing a short note of your symptoms to a prenatal visit makes the conversation easier, and Gale can help you prepare it.

Common questions

Occasional diarrhea is usually harmless and often comes from a stomach bug, food, or a diet or supplement change. It is less common than constipation and typically clears within a day or two.

Most bouts settle within 24 to 48 hours. Diarrhea that lasts longer, or that comes with dehydration, fever, or blood, is a reason to contact a prenatal provider.

Dark urine, urinating less than usual, a dry mouth, dizziness, a racing heart, or feeling faint suggest dehydration. Because fluid needs are higher in pregnancy, these signs deserve attention sooner.

Sometimes. In the final days before labor, hormone shifts can loosen the stool for some people. On its own it is not a reliable sign, but paired with regular contractions it can be part of early labor.

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When diarrhea in pregnancy needs prompt care

  • —Signs of dehydration — dark urine, very little urination, dizziness, or a racing heart — are a reason to contact your prenatal provider the same day.
  • —Diarrhea lasting more than 48 hours, or with blood or mucus in the stool, is a reason to seek clinician review.
  • —A fever alongside diarrhea, or severe or constant belly pain, is a reason to seek same-day medical care.
  • —In the third trimester, reduced fetal movement or regular cramping with diarrhea is a reason to seek urgent care.

This article is general health education, not medical advice. Whether diarrhea in pregnancy needs evaluation is best decided with your prenatal clinician, such as an obstetric provider, nurse practitioner, or midwife.

References

  1. 1.Office on Women's Health (U.S. HHS) (2025). Prenatal care. Office on Women's Health (womenshealth.gov), U.S. HHS. link ✓Office on Women's Health prenatal care overview describing dehydration warning signs and the symptoms that warrant contacting a prenatal provider.
  2. 2.National Institute for Health and Care Excellence (2024). Antenatal care (NG201). National Institute for Health and Care Excellence (NICE). link ✓NICE antenatal care guidance recommending assessment for pregnancy symptoms that are severe, persistent, or accompanied by feeling unwell.
  3. 3.American College of Obstetricians and Gynecologists (2021). Anemia in Pregnancy: ACOG Practice Bulletin, Number 233. Obstetrics & Gynecology. doi:10.1097/AOG.0000000000004477 ✓ACOG Practice Bulletin on anemia in pregnancy describing routine prenatal iron supplementation, which commonly alters stool and bowel patterns.

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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