Black stool during pregnancy is common, and there may not be any concerning causes in most cases. Dietary supplements, certain foods, food dyes, medications, and digestive changes in pregnancy can be the reason for the black pigment (1). Although avoiding the causative factor can change the stool color to normal, it is not recommended if there are no health issues.
However, if you experience any other symptoms or concerns, you may seek your doctor’s opinion. Read on to understand the reasons for black stool during pregnancy, how to prevent it, and when to seek medical care.
Common Causes Of Black Stool During Pregnancy
Black or tarry stools could be due to one or more of the following factors.
- Iron supplements: Doctors prescribe iron supplements if they see a deficiency. In some cases, your body cannot absorb, and this unabsorbed iron could give the stool black or tarry appearance (2).
According to Dr. Alan Lindemann, obstetrician, who was also a clinical associate professor at the University of North Dakota, Grand Forks, “The iron in pills will be black even if the pills don’t look very dark. Bleeding from your rectum is not the same thing as black stool from taking iron supplements. It’s just that iron is turned black by your digestive tract, whether it’s coming from the iron in blood or from iron supplements.”
- Foods: Certain foods, such as licorice and blueberries, may turn stools dark. Artificial food colors also can affect the color of the stool (3). You can identify the cause by maintaining a food journal.
- Medication: Medicines other than iron supplements might also cause the stools to turn black. Pepto-Bismol, which is one of the commonly used over-the-counter medications for an upset stomach, may also affect the stool color (4).
- Health issues: Digestive issues such as hemorrhoids, constipation, and anal fissures or tears during pregnancy (5) develop due to the increased pressure over the pelvic region, and this increases the odds of having fresh blood in the stool color.
- Bleeding: Bleeding within the digestive system, especially in the upper gastrointestinal tract (that includes the esophagus, stomach, and small intestine), could lead to dark-colored stools (6). The blood mixed with digestive juices can give a dark color to the stool.
Dr. Lindemann says, “If your stool is black, we say the blood is coming from higher up in your digestive tract because it is staying in your colon for a longer time, long enough to change the color to black. Although it is possible for you to have bleeding in your colon from a tumor, benign or malignant, it is extremely unlikely for a woman of 20 to 35 years. If you have a family history of colon cancer, you will probably want to have some kind of examination or testing after you deliver.”
Symptoms That May Accompany Black Stools
Depending on what the cause is, you may notice these symptoms along with black stools.
- Abdominal or chest pain
- Breathing difficulty
- Nausea or blood vomiting
If you notice dark stools along with these symptoms for an extended period, consult your health care provider to rule out any complications for both you and your baby.
How Can You Avoid Black Stools During Pregnancy?
Changes in your diet, medication, and hygiene habits might help you avoid dark stools.
- Consume iron-rich food: To avoid dark poop due to iron supplements, try and get as much iron as you can from dietary sources. Include more of the liver, red meat, dark green leafy vegetables, and iron-fortified cereals in your diet. Unlike supplements, foods are easily absorbed by the body and may not result in dark stools.
- Avoid OTC medications: Do not take any medications without consulting your doctor, as they may have certain side effects, including change in stool color.
- Increase fiber intake: Consuming food rich in dietary fiber can reduce the risk of constipation and hemorrhoids, and also protect your gastrointestinal tract (7). It is good to consult a dietitian and get a meal plan that suits your body’s needs during pregnancy.
- Have a healthy lifestyle: Refrain from smoking and alcohol consumption to lessen the chances of irritation of the upper gastrointestinal tract (that could lead to bleeding and black stools) (8). Also, try some Kegel exercises (only after doctor’s consultation) for improving muscle functioning around the rectal and vaginal areas. It can help regulate bowel movements and lessen the chances of constipation, bleeding, and other ailments.
- Stay hydrated: Sometimes, constipation due to dehydration can harden the stools as well as make them appear dark. So, drink at least 10 to 12 glasses of water, freshwater juices, and water-rich foods (cucumbers, watermelons) to avoid that.
How Is The Cause Behind Dark Stool Diagnosed?
The healthcare provider may study your medical history, do a physical examination, and order some tests. You may have to go for a combination of blood tests, x-rays, and stool examinations. If the results are inconclusive, the doctor may ask you to go for an endoscopy that will examine the gastrointestinal tract and help identify the cause. Based on the tests and results, you will be given the appropriate treatment.
Frequently Asked Questions
1. Can prenatal vitamins cause dark stools?
2. Is black stool one of the symptoms in the early stages of pregnancy?
Early in the pregnancy, you may notice some changes in the bowel patterns, and dark stools could be one of them if you are on iron and vitamin supplements. In some cases, the changing hormonal levels might slow down the stool movement, causing constipation that could make the stools hard and dark.
3. Is black stool a sign of miscarriage?
Black stool is usually not a sign of miscarriage.
Black stool during pregnancy isn’t uncommon. Consuming iron supplements, foods containing artificial colors, certain medications, and health conditions like constipation are common causes of black stool during pregnancy. In most cases, it isn’t a cause for concern. However, in some cases, it might indicate an underlying problem. Hence, consult your doctor if you experience abdominal discomfort or other bothersome symptoms with black stools. Making necessary dietary and lifestyle changes based on the underlying cause can also help you avoid it.
Infographic: Other Medical Reasons For A Dark Stool In Pregnancy
One of the most common reasons for dark stools during pregnancy is the side effects of certain medications or supplements. However, in rare cases, there may be more serious underlying causes, some of which are listed in the infographic below.
2. Scott LaFee; End Results: What color is your poop and other pressing fecal matters; UC San Diego (2018)
3. What Pee And Poo Color Says About Your Health; The American Council on Science and Health (2016)
4. Black or tarry stools; NIH (2018)
5. Gastroenterology; UCLA Health
6. Black or tarry stools; NIH (2018)
7. J. Clifford et al.; Dietary Fiber; Colorado State University
8. Gastritis; Harvard Health Publishing (2014)