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Why Does Newborn Spit Up Breast Milk

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Are you a new parent wondering why your newborn is spitting up breast milk? Don’t worry, it’s actually quite common. In fact, up to 70% of infants experience spit up at least once a day during their first few months of life.

Spit up occurs when your baby’s stomach contents come back up through their mouth or nose. While it can be alarming to see, it’s rarely a cause for concern and typically resolves on its own as your baby’s digestive system matures.

Let’s dive deeper into why this happens and what you can do to help reduce the frequency of spit ups in your little one.

Understanding the Commonality of Spit Up in Newborns

You’ll notice that many newborns frequently spit up small amounts of milk during or after feedings. This is actually quite common and typically not a cause for concern.

In fact, about half of all babies experience some degree of spitting up in their first few months of life.

One reason for this is that newborns have immature digestive systems. Their lower esophageal sphincter (LES), which is responsible for keeping food in the stomach, may not be fully developed yet.

As a result, breast milk can easily flow back up into the esophagus and out of the mouth. Additionally, newborns tend to eat frequently and quickly, which can lead to overfeeding and subsequent spitting up.

Exploring the Development of Your Baby’s Digestive System

You may have noticed that your newborn spits up breast milk frequently. This is because their lower esophageal sphincter, which controls the passage of food from the esophagus to the stomach, is still immature and not fully developed.

Additionally, their small stomach capacity means that they need to eat more frequently and in smaller amounts, which increases the chances of milk being regurgitated.

Immature Lower Esophageal Sphincter

Your baby’s lower esophageal sphincter isn’t fully developed, which means the muscle responsible for keeping food in their stomach isn’t working properly yet.

This can result in your newborn spitting up breast milk after feeding.

The lower esophageal sphincter (LES) is a circular muscle located at the bottom of the esophagus, and it opens to allow food to pass into the stomach.

In adults, it closes immediately after food enters the stomach to prevent acid reflux, but in babies, this mechanism may not be fully functional.

When your baby feeds, milk travels down the esophagus and into their stomach.

If the LES doesn’t close tightly enough or if it opens too frequently, some of the milk may flow back up into their mouth causing them to spit up.

This usually happens within minutes after feeding or during burping.

It’s important to note that spitting up small amounts of breast milk is normal for most infants and doesn’t necessarily indicate a problem with digestion or nutrition.

Small Stomach Capacity

It’s tough when your little one seems to be constantly hungry, but their small stomach capacity means they can only handle so much at a time. Newborns have tiny stomachs that can only hold about 1-2 ounces of milk per feeding. As they grow, their stomachs will also increase in size and they’ll be able to consume more milk at once.

To give you an idea of how small your baby’s stomach is, take a look at the table below:

AgeStomach Size
Day 1Marble-sized (5-7 ml)
Day 3Cherry-sized (22-27 ml)
Week 1Ping Pong ball-sized (45-60 ml)

As you can see, your newborn’s stomach is incredibly small! This means that if you try to feed them too much breast milk at once, their body may not be able to handle it and they could end up spitting it back up. It’s important to remember that frequent feedings throughout the day are normal for newborns and will help ensure that they’re getting enough nutrition without overloading their tiny tummies.

The Role of Feeding Position in Spit Up

Adjusting your feeding position can greatly reduce the amount of milk that your baby regurgitates. When you hold your baby in a slouched or reclined position during feedings, it can cause milk to flow more quickly and easily into their mouth. This may cause them to swallow more air, which can lead to spitting up.

Instead, try holding your baby in an upright position during feedings, with their head slightly elevated above their stomach. This will allow the milk to flow at a slower pace and prevent excess air intake.

Another factor to consider is the angle of your baby’s head while feeding. If their head is turned too far to one side, it can cause them to swallow air along with the breast milk. Make sure that their nose is aligned with your nipple and that they are facing towards you directly while feeding.

You can also try switching sides during feedings so that each breast gets equal stimulation and your baby has a chance to change positions as well. Remember that every newborn is different, so don’t be afraid to experiment with different positions until you find what works best for both you and your little one.

When to Seek Medical Attention

If your baby is consistently spitting up large amounts or showing signs of discomfort after feedings, it may be time to seek medical attention. While spitting up is common in newborns, excessive vomiting or difficulty gaining weight could be a sign of an underlying issue. Here are some warning signs that indicate you should take your baby to the doctor:

Warning SignsWhat They Could Mean
Projectile vomitingGastroesophageal reflux disease (GERD)
Blood in vomit or stoolMilk allergy or gastrointestinal bleeding
Difficulty breathingAspiration or pneumonia
Refusal to eatOral thrush or other infection

It’s important to note that spitting up breast milk alone does not necessarily warrant a trip to the doctor. However, if you’re concerned about your baby’s health, don’t hesitate to contact your pediatrician. Trusting your instincts as a parent and seeking help when needed can ensure that your little one stays healthy and happy.

Frequently Asked Questions

Can spitting up breast milk cause harm to my newborn?

Spitting up breast milk is a common occurrence in newborns and isn’t usually a cause for concern.

In fact, most babies will spit up some milk after feedings.

This is because their digestive systems are still developing, and the muscles that control the entry and exit of food in their stomachs aren’t yet fully developed.

While it may be messy and inconvenient, spitting up breast milk doesn’t typically harm your baby.

However, if you notice that your baby is consistently vomiting or appears to be in discomfort during or after feeding, it may be worth consulting with your healthcare provider to rule out any underlying issues.

How long does it take for a newborn’s digestive system to mature?

When your newborn enters the world, their digestive system isn’t fully developed. It takes time for their body to adjust and get used to processing breast milk efficiently.

As a result, it’s normal for babies to spit up frequently in their first few months of life. However, with time and patience, their digestive system will mature and become better equipped to handle breast milk without spitting up as often.

Keep in mind that each baby develops at their own pace and some may take longer than others to reach this milestone. Just remember to be patient and consult with your pediatrician if you have any concerns about your baby’s feeding habits or digestion.

Is it normal for my newborn to spit up after every feeding?

It’s common for newborns to spit up after every feeding. This is because their digestive system is still developing and not yet fully matured.

Additionally, newborns tend to eat frequently and in small amounts, which can lead to overfeeding and subsequently, spitting up.

However, if your baby seems uncomfortable or experiences other symptoms such as vomiting forcefully or refusing to eat, it’s important to consult with a pediatrician as this could indicate a more serious issue.

Can my diet as a breastfeeding mother affect my newborn’s spit up?

If you’re a breastfeeding mother, it’s important to know that what you eat can have an impact on your newborn’s spit up. Certain foods and drinks, such as caffeine, spicy foods, dairy products, and citrus fruits, may cause your baby to spit up more frequently or experience discomfort.

It’s recommended to keep track of what you eat and how it affects your baby’s digestion. In most cases, adjusting your diet can help reduce the frequency and severity of spit-ups in newborns. However, if the problem persists or worsens over time, it’s best to consult with a pediatrician for further evaluation and advice.

How can I prevent my newborn from spitting up during sleep?

To prevent your newborn from spitting up during sleep, there are a few things you can try.

First, make sure they’re positioned correctly during feedings to minimize air intake.

You may also want to try smaller and more frequent feedings rather than larger ones less often.

It’s important to burp your baby after each feeding and keep them upright for at least 20-30 minutes afterwards.

Additionally, avoid jarring movements or activities immediately after feeding and consider using a wedge or elevated sleeping surface to keep their head slightly elevated while they sleep.

Remember that some amount of spit up is normal for babies, but if you have concerns about the frequency or amount, always consult with your pediatrician.


In conclusion, spitting up is a common occurrence in newborns and not necessarily a cause for concern. Your baby’s digestive system is still developing, which can lead to some milk coming back up.

However, there are ways you can help reduce the frequency of spit up such as adjusting your feeding position.

Remember that if your baby seems uncomfortable or is spitting up excessively, it’s always best to consult with your pediatrician. They can help determine if there may be an underlying issue causing the excessive spit up and provide guidance on how to address it.

But rest assured that in most cases, spit up is simply a normal part of infancy and will eventually lessen as your baby’s digestive system matures.

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