Causes of Mucus in a Breast Fed Baby's Stool

A baby's stool will change color, shape, odor and frequency numerous times, especially throughout the first year of life. A breastfed baby's stools are often softer, milder in odor and more yellow compared to those of a formula-fed baby. Noticing mucus in the stool can be alarming, but it often has a normal explanation.

Some causes of mucus in a baby's stool are serious, however. Caregivers should report any concerns to a medical care provider.

Normal Secretions

Mucus lines the intestines to assist in pushing waste out of the body.

It is not unusual to have a small amount of mucus cling to the fecal matter. Dr. Hull points out that in a breastfed baby, most of the stool matter is made up of mucus because the baby uses breast milk so efficiently that very little waste remains.

Food Allergy


Green Stool in a Teething and Nursing Baby

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Despite being breastfed, an infant can still have some allergies to foods that his mother eats. Foods and even flavors pass through the milk to the baby.

An infant's immature digestive system may not tolerate dairy products or spicy foods that the mother has consumed.

A breast-feeding mother who notices that her baby has excessive gas, fussiness or projectile vomiting and sees mucus in her infant's stools can keep a food journal to identify the cause of the baby's discomfort. An elimination diet can also be helpful in ruling out other issues. In this diet, a mother avoids all dairy products for a period of time, for example, one week, and observes her baby's response.

Intestinal Irritation

Mucus that appears in diarrhea is the result of the colon producing more natural secretions to keep the tissues moist and lubricated according to the Mayo Clinic. Any intestinal irritation, such as infection, can also cause mucus to appear in the stool. Often the mucus is accompanied by blood. eMed TV points out that viral infections are the most common cause of diarrhea, but bacterial infections are another potential cause.

Bacterial infections are most likely to cause blood and mucus in the stool. Breastfed babies can pick up infections from putting contaminated items in their mouths or from improperly stored expressed breast milk.



Smelly Bowel Movements in Infants

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Intussusception is a more serious cause of mucus in the stools. Kids Health explains that this disorder is most common in children between the ages of 3 months and 6 years. The condition occurs when one section of the bowel slides into the next, creating an obstruction of the bowels.

The result is a diminished blood flow to the intestines, swelling and inflammation.

When intussusception first occurs, a baby will feel sharp pain, and more intermittent pain follows.

Stool symptoms include passing mucus and blood that resemble jelly, called currant jelly stool.

This symptom appears in 60 percent of infants with intussusception. Other symptoms include vomiting, lethargy, shallow breathing and grunting. Medical treatment is necessary to correct the bowel obstruction.