Blood in a Newborn’s Stool: What Could It Mean?

What Can Blood in a Newborn's Stool Look Like?

Fresh blood is usually bright red. You may see a streak or a few small flecks. The blood may sit on the stool or appear on the diaper.

Blood from higher in the digestive tract may look dark. It can turn the stool black and tar-like.

Blood may also appear with mucus or diarrhea. Take a clear photo before you discard the diaper. If possible, save the diaper for your baby's doctor.

Could It Be an Anal Fissure?

Yes. An anal fissure is a small tear in the skin at the anus. It can leave a few bright red streaks on the stool.

Your pediatrician may see the tear during an exam. Still, do not assume a fissure is the cause. Bright red blood in infant stool needs medical guidance when the baby is a newborn.

Could the Blood Have Come From Mom?

Sometimes a newborn swallows maternal blood during birth. A breastfed baby may also swallow blood from a cracked or bleeding nipple.

The swallowed blood may later appear in spit-up or stool. Your baby's clinician can help decide if the blood came from the baby or the mother.

Could a Food Protein Allergy Cause It?

Yes. Food protein-induced allergic proctocolitis, or FPIAP, can inflame the lower bowel. Cow's-milk protein is the most common trigger.

FPIAP may cause loose or slimy stools with red streaks. Many babies with it still look well. They may also feed and grow normally.

Cow's-milk protein can come through formula. In some breastfed babies, milk protein in the parent's diet may play a role.

But blood in newborn stool does not prove a milk allergy. Other food allergies and nonallergic problems can cause similar signs. Your pediatrician should assess the whole picture first.

Does My Baby Need Special Formula?

Not always. One unusual diaper is not enough reason to keep switching formula.

If milk protein is the likely cause, your doctor may suggest an extensively hydrolyzed formula. Some babies need an amino-acid formula. These are not the same as standard “gentle” or “sensitive” formulas.

Choose formula based on a medical plan, not guesswork.

Should a Breastfeeding Parent Stop Dairy?

Not without medical advice. Most breastfed babies do not need the parent to avoid dairy after one odd stool.

If your doctor suspects FPIAP, a supervised dairy-free trial may help. Discuss the plan before removing a major food group. This protects both the diagnosis and the parent's nutrition.

Could an Infection Cause Bloody Stool?

Yes. Some intestinal infections cause bloody diarrhea or mucus in bowel movements.

A sick newborn may also have fever, vomiting, poor feeding, or unusual sleepiness. Infection and fluid loss can become serious quickly at this age. Seek care promptly for bloody diarrhea.

Could It Be a Serious Bowel Problem?

Less often, bloody stool is a sign of serious bowel disease. Warning signs include a swollen belly, repeated vomiting, green vomit, poor feeding, weakness, or unusual sleepiness.

Premature or medically fragile babies can develop necrotizing enterocolitis. This is a serious bowel illness that needs immediate care.

These problems are less common. But they explain why blood in a newborn's diaper should never be dismissed as a simple formula problem.

What About Black Stool?

A baby's first stools are dark green or black, thick, and sticky. This normal first stool is called meconium.

After the meconium days, new black or tar-like stool is not normal. It may be digested blood from higher in the digestive tract. Call for prompt medical care.

Dark green stool may look black in poor light. Save the diaper or take a photo if you are unsure.

When Should I Call My Pediatrician?

When Is Blood in the Stool an Emergency?