Understanding Blood in Your Baby's Diaper

Finding blood in your baby’s stool or diaper can be concerning—especially for new parents—but it’s often caused by common, manageable issues. There are several reasons you might find red or pink stains in your baby’s diaper, ranging from mild skin irritation and small anal fissures to food sensitivities or harmless color changes in stool. In most cases, these issues are temporary and not serious, but it's essential to be aware of what to look out for.

This guide explains the most common reasons for blood in a newborn’s or infant’s stool or diaper, what it typically looks like, and when it’s time to contact your baby’s healthcare provider. Understanding the difference between normal variations and signs that need medical attention can help you stay calm, confident, and informed as you care for your little one.

Common Reasons for Blood in an Infant’s Stool or Diaper

Seeing blood in your newborn or older baby’s stool or diaper can understandably cause concern. The causes of blood in a baby’s poop or diaper range from mild digestive irritation to less common medical conditions.

Below are the most common reasons, what it typically looks like, and when medical advice is recommended.

When Red Stool Isn’t Actually Blood

Seeing red or pink in your baby’s poop doesn’t always mean it’s blood. In some cases, changes in stool color are related to what your baby has eaten rather than true bleeding.

Once babies begin eating solid foods—typically around 6 months of age—certain foods can cause red-tinted stools that may look like blood in a baby’s diaper. Common examples include:

• Foods that cause blood-like coloring in stool, such as beets

• Foods or drinks containing red food coloring

• Certain medications

• Iron supplements, which can darken stool and sometimes appear reddish or brownish.

If your baby is younger than 6 months and not yet eating solids, red stool is less likely to be food-related and should be discussed with your baby’s healthcare provider.

These food- or supplement-related color changes are usually harmless and temporary. If your baby seems comfortable and otherwise well, the stool typically returns to its usual color on its own.

The right diaper can make a difference—especially during messy or sensitive moments. Take our quick quiz to find the best diaper for your baby’s needs.

Anal Fissure

An anal fissure is the most common reason for blood in an infant’s stool and accounts for the majority of cases of rectal bleeding in newborns, babies, and children.

This usually happens when a baby passes a firm or large stool, causing a tiny tear in the delicate skin around the anus. You may notice:

• Bright red streaks on the stool

• Blood on the diaper or baby wipe.

Infant constipation is often a cause of anal fissures and, therefore, blood in the stool. If your little one is experiencing hard stools, try our strategies for relieving constipation to reduce discomfort and prevent fissures.

Although seeing blood can be alarming, anal fissures are usually small, heal on their own, and are not dangerous. Keeping stools soft and the diaper area clean can help prevent recurrence.

Food Allergies

Food sensitivities—most commonly a cow’s milk protein allergy—can sometimes cause blood in an infant's stool, especially in younger and formula-fed babies.

This may appear as:

• Small streaks of blood

• Bloody mucus in stool

• Fussiness or feeding discomfort.

Milk protein allergy can affect both formula-fed babies and breastfed babies (through dairy in the breastfeeding parent’s diet).

If you suspect a food allergy, your baby’s healthcare provider may suggest dietary changes or a different formula. Always consult them before making feeding changes.

Swallowed Blood

If you notice blood in your breastfed baby’s stool, one possible explanation is swallowed blood.

This may occur if:

• The breastfeeding parent has cracked or bleeding nipples

• Your baby recently had a nosebleed

• Blood was swallowed during birth or a medical procedure.

Swallowed blood can pass through the digestive system and show up as blood in a breastfed infant's stool. While usually harmless, persistent blood should be discussed with your provider.

Bacterial or Parasitic Infection

In rare cases, a bacterial infection might cause blood in the stool, or a parasitic illness may be responsible.

These infections may cause:

• Diarrhea

• Fever

• Abdominal discomfort

• Blood in baby poop that may be darker or mixed throughout the stool.

A urinary tract infection can cause blood in the urine, rather than the stool. If you notice blood in the diaper and your baby seems unwell, such as fever, vomiting, or abdominal pain, contact their healthcare provider immediately.

Urate Crystals

One common cause of concern in newborns is urate crystals in a diaper, which can look like pink, red, or rust-colored stains.

Urate crystals are:

• Concentrated urine salts

• Common in the first few days of life

• Often mistaken for blood in newborn pee.

They usually appear as a blood spot in a baby's diaper, but are not actually blood in the urine. Urate crystals often resolve as feeding increases and hydration improves.

You can discover more about baby pee and what to expect in our dedicated guide.

Diaper Rash

Parents sometimes ask, “Can diaper rash cause bleeding?” In some cases, yes.

Severe diaper rash can cause skin breakdown, leading to:

• Small spots of blood

• Oozing or irritation.

Keeping the diaper area clean and dry and using barrier creams may help protect irritated skin. If bleeding continues, check with your baby’s healthcare provider. You can learn more about diaper rash bleeding in our dedicated guide.

Other Severe Conditions

In rare cases, blood in a baby’s stool may indicate a more serious condition. These could include issues like intestinal inflammation, blockages, or congenital abnormalities.

Examples include:

• Upper gastrointestinal bleeding

• Intestinal blockages

• Necrotizing enterocolitis (NEC)

• Inflammatory bowel disease (IBD)

• Meckel diverticulum

• Polyps.

These conditions are uncommon but may require immediate attention. If you’re concerned about persistent or significant blood in your baby’s stool, consulting your child’s healthcare provider is the best course of action.

Blood in a Newborn Girl’s Diaper

If you notice blood in a baby girl’s diaper, it may not always come from the stool. In some cases, blood in a newborn's pee or a blood spot in the diaper could be mistaken for stool-related bleeding.

For female infants, it’s common to observe a small amount of blood in the diaper due to a "mini-period" or false menses. This occurs as a result of hormonal changes passed from the birth parent to the baby during pregnancy. This process is normal and indicates a healthy uterus, so there’s no cause for concern.

If you’re unsure whether the blood is from the urine, stool, or elsewhere, or if you notice persistent bleeding, consult your baby’s healthcare provider for reassurance and guidance.

Treatment for blood in your baby’s stool or diaper depends on the cause and may include:

• Addressing constipation to soften stools

• Managing diaper rash or skin irritation

• Adjusting feeding under medical guidance

• Treating infections if present.

Your baby’s healthcare provider will determine the appropriate approach based on your baby’s symptoms and overall health.

When to Visit Your Healthcare Provider?

If you notice blood in your baby’s stool, it’s natural to feel concerned. While many causes, such as minor anal fissures or dietary factors, are harmless and temporary, there are times when reaching out to your healthcare provider is essential.

Your little one’s healthcare provider may evaluate the situation and, if necessary, recommend appropriate tests or treatments. Trust your instincts. If something feels off, it’s always best to consult a professional.

The Bottom Line

Finding blood in your baby's diaper can be alarming, but many causes are minor and manageable. From simple issues like constipation to more serious concerns, understanding your baby's stool, including its color and consistency, can help ease your worries. If you’re ever unsure or notice ongoing symptoms, consulting your baby’s healthcare provider is the best course of action. Being informed can provide peace of mind as you care for your child.

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