Why Does My Baby Spit Up Breast Milk But Not Formula (Causes & Prevention Tips)

The most common reason babies spit up breast milk but not formula is because formula milk is a controlled diet for babies. You measure exactly how much you want to feed your baby. With breast milk, sometimes, you’re over-feeding your little one, or the flow of the milk is faster, making the baby gulp air along with breastfeeding. Other possible reasons are that your baby might be allergic to certain food content that’s present in your breast milk, or there’s an imbalance between foremilk/hindmilk feed.

Hi there, dear worried-parent,

The most common thing a baby does other than eating, sleeping, and pooping is spitting up. More than oftentimes, babies who spit up are considered “happy spitters”-under the condition that the baby is calm and has no breathing issues, or choking or wheezing isn’t combined with the spit-up.

It’s common and expected for babies to spit up after feedings and sometimes after every feed. It’s their way of releasing the air they gulped while feeding, and so sometimes, they have a wet burp, where a small amount of milk or curdled milk comes out along with their burp.

Every parent wants their child to eat happily, gain weight, and achieve all milestones. So, when a baby throws up, it can cause worry among mothers or caregivers, which is completely normal too.

When my son was 8 weeks old, he would throw up after every feed. What was the reason? I had an oversupply of milk. So, when he breastfeeds, the flow of the milk is so quick, and the letdown is so much that he would aggressively drink a lot of milk along with swallowing air.

So, it was normal when he spit up the breast milk because of overfeeding. Babies are born with a stomach that is the size of a cherry.

So, they tend to get full and hungry quicker, and because their digestive system is still developing, they tend to throw up some amount of milk after each feeding.

My son’s pediatrician told me to give my worries a rest as long as the baby seems comfortable and calm after throwing up and it’s not projectile or forceful vomiting.

Why does baby spit up breast milk and not formula?

Mom is trying to breastfeed her newborn, who has been spitting up a lot more lately.

There are multiple reasons for newborns to spit up milk after every feed. First, a baby’s digestive system till the age of 6 months is weak and is still developing. So, there are more chances of a baby spitting up milk during this time.

The medical reason behind this is (to put simply) – as a baby feeds, the milk goes down the throat, and through the esophagus, and finally reaches the stomach.

The esophagus is connected to the baby’s stomach by a ring of muscles called the lower esophageal sphincter, which opens to let the milk flow in the stomach and closes immediately.

But, this “door” that opens and closes to let the milk in the stomach isn’t very reliable and doesn’t necessarily close immediately, which in turn causes a backflow of milk, resulting in a spit-up.

The primary reason is the stomach, and the “door” are still developing and will be more mature around the time the baby is 6 months of age. Till then, the spit-up may happen frequently and is quite normal.

Other major reasons for babies to spit up breast milk

1. Overeating or swallowing air during feedings

When a baby eats too much or too fast, she can tend to throw up more milk because her stomach isn’t able to handle that much amount of the liquid gold, or when the mother’s let-down is too fast that the baby swallows the milk quickly, and with it gulps in the air too, causing her to burp and throw up some milk along with it.

2. Sensitivity or allergic to certain foods in mother’s diet

There’s a chance that your baby’s frequent spit-ups only after drinking breast milk is that she can be allergic or sensitive to certain foods or drinks present in the mother’s milk, making the baby throw up after breastfeeding.

Allergens can be transferred through the breast milk and cause your baby to throw up.

3. Imbalance of foremilk and hindmilk

If the mother doesn’t feed her little one correctly, there can be an imbalance between the baby’s intake of foremilk and hindmilk, causing some babies to spit up a lot after breastfeeding.

Know the correct way of latching your baby and the breastfeeding technique to give your baby the right amount of foremilk and hindmilk needed.

So, the question remains- why doesn’t my baby spit up after drinking formula as much as she spits up after breastfeeding?

Well, as said earlier, formula milk is a controlled diet. You will measure and give your baby the milk, and you will know how much oz of milk satisfies your little one every time.

But, with breast milk, you can have an oversupply of milk, causing your baby to throw up the excess milk consumed.

Another reason is that the formula has the same type of nutrients every time you give it to your baby, but it’s a completely different ball game with breast milk.

Breast milk is dependent on the mother’s diet. So, the taste and the nutrients present can change depending on what the mother eats.

So, if the baby is sensitive or allergic to certain foods the mother has consumed, it will become difficult for the baby to digest the milk- resulting in the baby throwing up.

Ways you can reduce your baby’s spit-ups

  • Burp your baby after every feed and during the feed when you change breast sides.
  • Avoid playing actively with the baby for 30 minutes after feeding.
  • Avoid placing her on a rocking or a bouncy chair for 30 minutes after feeding.
  • Because the let-down milk varies in different rates at different times- try to give smaller feedings multiple times, instead of large feedings with an increased gap in between.
  • If you have a faster let-down, then feed your baby in a reclined position, so that she’s taking the milk against gravity.
  • If you have an engorgement, try relieving it by pumping or expressing your milk before breastfeeding, so that it’s easier for the baby to latch properly.
  • You can also try using anti-colic feeding bottles to feed your breast milk to the baby.
  • Make a note of your diet and if you feel certain foods you consume is making the baby’s stomach upset, then try cut them out from your diet for a while.


How can you tell the difference between vomiting and spit-up?

When a baby spits up, it tends to be an easy milk flow through her mouth and comes with a burp. While the flow of milk with vomiting will seem forceful and will seem like projectile vomiting, shooting out inches rather than just dribbling milk from the mouth.

Breast milk or formula– Which makes the baby feel fuller?

Because the formula is thicker in consistency than breast milk, babies tend to feel full for a longer time after drinking formula. But, breast milk is easier to digest, and babies can feel full with frequent smaller breastfeeding sessions.

What should I do if the baby doesn’t burp after breastfeeding and falls asleep?

In such cases, try burping them for a minute before laying them on their back. Sometimes babies don’t burp in the nighttime because they tend to eat slower and so don’t swallow much air while feeding.


One simple thing I’ll tell you is- spitting up is quite normal for babies as long as they don’t seem distressed after it, and the spit-up doesn’t seem like vomiting large amounts of milk.

If your baby tends to spit up often after breastfeeding, then try experimenting with different breastfeeding positions, burp them often, and relieve yourself first in case of engorgement before feeding, and try not to let the baby be very active within 30 minutes of breastfeeding.

Even bottle-fed babies tend to spit up a lot after feeding. So, in such cases, use anti-colic bottles which limit the baby from swallowing air while feeding.

Meanwhile, stay calm and happy, and if you’re still worried about your little one- you can always reach out to your baby’s doctor.

Happy feeding!

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Located in India and a mother to a joyfully mischievous son, Kelin is the wife of the world’s most patient man and a busy homemaker. When she’s not busy cooking and running after her kid,  you can find her in a corner reading, or penning down words on her laptop. She believes the world will always try to instil ‘mom guilt’ in new mothers, but she goes by the maxim ‘a mother knows best'.

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