Why Do Babies Spit Up Breast Milk and Formula?

As a parent, it's normal to worry about your little one, and often, it can seem like there is an endless list of things to stress about. A common source of anxiety amongst parents is wondering why their baby is spitting up.

Understandably, watching your baby spit up may cause you distress. On top of that, you're likely worried about whether or not your baby is getting enough food. The odds are that you're getting tired of cleaning up your baby, yourself, and whatever else has fallen victim to being the target of your baby's spit-up.

You probably think it's a bad sign that your baby's food isn't staying down. Well, to put some of your fears to rest, spitting up, also known as infant reflux, is normal and not a cause for concern for most babies.

In this article, we'll explain why spitting up is so common among babies, what kind of spit-up is normal, tips and tricks for reducing it, and red flags to watch out for!

Why Do Babies Spit Up After Eating?

It's normal for babies to spit up after a feeding and, in some cases, after every feeding. About half of all infants will experience spitting up during their first three months of life. Pediatricians often refer to infants who spit up frequently but are otherwise healthy and happy as 'happy spitters.'

A 'happy spitter' is still thriving, growing well, generally content and comfortable, and has no issues related to vomiting but does deal with spitting up. But why is this the case? Typically, it comes down to your infant's digestive system not yet reaching maturity.

When your baby feeds on either breast milk or formula, the milk first journeys down your baby's throat, then to the esophagus, and the final destination is your baby's tummy.

Thankfully, our bodies are built with a handy mechanism known as the lower esophageal sphincter. Think of it as a little gateway that keeps our stomach contents where they belong: in our tummies!

The problem is that this gateway isn't as efficient as it should be before 6 months of age when your baby's digestive system is still developing.

While theoretically, your little one's stomach should be milk's next stop before reaching the intestines, milk often finds its way back through the gate, then up and out for your baby's mouth.

This is often especially true if your baby eats too much or too quickly because once their tiny tummy fills up before passing the milk to the intestines, the only place left for the rest is out!

Learn More: Baby Feeding Chart: Recommendations for the First Year of Life  

Ultimately, whether your baby is breastfed or formula-fed or takes a combination of both, there's a good chance that your baby spits up. In most cases, an underdeveloped lower esophageal sphincter is the culprit. But can the causes of spit-up differ depending on what your baby drinks? Read on to learn more!

Do Babies Spit Up Breast Milk?

For breastfed babies, spit-up can sometimes be related to your infant's sensitivities or allergies to certain foods in your maternal diet. These allergens can then be passed on to your child through nursing which can provoke spit-up. In such cases, your child's pediatrician may recommend that you eliminate dairy products or other foods from your diet.

Alternatively, an overabundant milk supply or a strong let-down reflex can increase the air your baby takes in while feeding.
The combination of gulping down large amounts of air and milk can cause spit-up. You can usually help prevent air from mixing with your baby's stomach contents if you regularly burp your baby both during and after feedings.

Why Do Babies Spit Up Formula?

Similar to some breastfed babies having allergies to components of their mother's diet, formula-fed babies may have milk/soy protein intolerance or allergy, leading to spitting up their formula. In such cases, it's best to contact your baby's doctor, who can suggest a formula without these ingredients.

Learn more: When to Use Hypoallergenic or Special Formula?

Furthermore, air can also cause spit-up in bottle-fed babies. If you bottle-feed your little one, it's important to choose a baby bottle with an adequately sized nipple hole.

If you choose a nipple that's too small, it can cause air bubbles to fill your baby's stomach with swallowed air. When you hold your baby's bottle upside down, their formula should ideally flow at the speed of one drop per second. Cleaning or replacing the nipple should help combat this issue!

What is a Normal Amount of Spit-Up?

Alright, so now we know that spitting up in babies is very common, but how can you tell how much spit-up is normal? It's important to mention that normal amounts vary widely regarding baby spit-up.

Your little one may experience a couple of dribbles down their chin to soak your entire shirt sleeve. It largely depends on the individual baby. However, if you're looking for an exact quantity to go off of, normal spitting-up usually produces between one and two tablespoons of spit-up.

We know it can be scary when the amount of spit-up looks like more than it is, but remember that if your baby is healthy, growing, comfortable, and gaining weight, there is likely nothing to worry about. Contact your baby's doctor if you're ever concerned about the amount.

What Is the Difference Between Spitting Up and Vomiting?

While spit-ups are common among many babies, true vomiting is different. Vomiting is usually a symptom of an underlying illness, and as such, it often appears alongside other symptoms, such as diarrhea or fever. We'll walk you through the important differences between the two, so you know what's what!

Spitting Up

Most spit-ups begin with a burp; then milk gently dribbles from your baby's mouth. The coloration can change slightly daily, but it should generally be cream, white, or yellow.

When your little one spits up, even after each time you feed your baby, it's often not an issue. If your baby is going to spit up, generally, the condition will present itself before 6 months of age, and you'll be happy to hear that most babies stop spitting up by 12 months of age.

Vomiting

On the other hand, vomiting occurs forcefully and will commonly shoot out of your infant's mouth and is accompanied by a retching sound. Your baby's stomach vile will typically tinge the vomit slightly green.

Most infants will vomit every once in a while, but if you find your baby is repeatedly vomiting for more than 24 hours, or if the color is red or green, it's important to contact your baby's pediatrician right away as it could be a sign of a serious health issue.

Other red flags that necessitate seeking medical attention include poor weight gain, dehydration, pain or discomfort, and if your baby is inconsolable.

Can Spitting Up Be a Sign of a Problem?

While spit-up is very common in healthy babies, it's not always smooth sailing. Occasionally, other symptoms can point toward a more serious issue than just day-to-day spitting up.

If you notice any of the following signs in your child, be sure to reach out to your baby's pediatrician:

• Not gaining weight
• Spits up forcefully
• Projectile vomiting
• Has fewer wet diapers
• Spits up brown, green, or yellow fluid
• Spitting up starts at 6+ months of age 
• Continually refuses their feeding
• Increased irritability

Gastroesophageal Reflux Disease

For some babies, gastroesophageal reflux disease (GERD) may be the culprit of their spit-up. When the sphincter in a baby's esophagus doesn't immediately close up after opening, the term ''acid reflux'' describes the spit-up coming back up alongside stomach acids and juices.

Symptoms of GERD include...

• Refusing feedings
• Crying or appearing in pain during a feeding
• Wheezing
• Coughing
• Swollen or hard belly
• Increased intensity or occurrence of spitting up
• Spit-up contains blood or is greenish

If you notice any of these symptoms, poor growth, or an inability to gain weight, contact your baby's doctor to determine if GERD may be the root cause of your baby's spitting up.

What Can You Do To Reduce Spitting Up?

Infant reflux is no fun for anyone, but the good news is that there are some things you can do to help reduce spitting up! We've prepared a top 5s list of things you can do to help. As always, consult your pediatrician to find the best strategy for your baby!

1. Avoid placing your baby on their stomach to sleep - According to the American Academy of Pediatrics, the best sleep position for a baby is on their back. Back sleeping helps to prevent SIDS and may reduce the incidence of spit-up!

2. Hold your baby upright after feeding - Holding your baby upright helps prevent milk from returning. For the best results, be sure to hold them upright for at least 20 to 30 minutes.

3. Make feeding synonymous with calm - By avoiding active play and limiting noise and bright lights during feeding time, you can help create more calm for your baby, which may work to reduce spitting up.

4. Avoid overfeeding your baby - According to the American Academy of Pediatrics, parents should wait at least two and a half hours between formula feedings and at least two hours between breast feedings. This will help your little one's stomach empty before adding more milk.

5. Burp your baby - When feeding your infant, hold your baby's head higher than the rest of their body and burp your baby during and after feedings to remove air from their belly. FYI, bottle-fed infants tend to be more prone to swallowing air and may need more burping.

Conclusion

Spitting up is just a normal part of the course for many healthy babies. While it can certainly be a nuisance to you who's constantly changing you and your baby's clothes, it's oftentimes not a cause for concern.

As long as your little one is gaining weight and not displaying any concerning symptoms with their spit-ups, everything is likely okay! But there certainly are cases in which spitting up crosses the line into abnormal or in which it's vomiting. So if you're ever in doubt about what is and is not normal for your baby, reach out to your baby's pediatrician!

Sources

• Spitting up in babies. Family Doctor. May 14, 2020. 

• Your baby: Spitting up and vomiting. Web MD. August 21, 2020. 

• Why babies spit up. Healthy Children. April 09, 2019.   

• Spitting up - Reflux. Seattle Children’s Hospital. 2022.