Babies spit up milk primarily because the muscle at the top of their stomach (the lower esophageal sphincter) is still developing and isn't fully closed.
Here's a more detailed explanation:
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Immature Sphincter: The lower esophageal sphincter (LES) acts as a valve between the esophagus and the stomach. In babies, this muscle is often loose and doesn't close tightly. This allows milk to flow back up into the esophagus and out of the mouth, resulting in spit-up.
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Mostly Milk, Not Acid: In healthy babies who are gaining weight normally, the spit-up consists mainly of milk and a small amount of stomach contents. It's usually not highly acidic, which is why it doesn't typically cause significant discomfort.
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Peak and Resolution: Spitting up usually peaks around 4 months of age and typically resolves by 7 to 12 months as the LES strengthens and the baby spends more time upright.
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Normal vs. Problematic: It's important to differentiate between normal spitting up (also known as gastroesophageal reflux - GER) and gastroesophageal reflux disease (GERD). GERD involves more severe symptoms like poor weight gain, irritability, forceful vomiting, or signs of discomfort during or after feeding. If you're concerned, consult with your pediatrician.
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Things to Try: While normal spitting up is often a laundry issue more than a medical one, there are a few things you can try:
- Burp frequently: Burping helps remove air bubbles that can contribute to spit-up.
- Hold the baby upright after feeding: Keeping the baby upright for about 30 minutes after feeding can help prevent milk from flowing back up.
- Feed smaller amounts more often: Overfeeding can exacerbate spit-up.
- Avoid tight diapers: A tight diaper can put pressure on the abdomen.
- Consider thicker feeds (only if recommended by your pediatrician): Your doctor might suggest thickening the baby's formula or breast milk with rice cereal, but this should only be done under their guidance.
If you notice concerning symptoms such as projectile vomiting, blood in the spit-up, refusal to feed, significant irritability, difficulty breathing, or poor weight gain, seek medical advice from your pediatrician. These symptoms could indicate a more serious underlying condition.
