Why Do Babies Spit Up, and What Causes It?

Spit-up is an unavoidable rite of passage when it comes to taking care of a baby. It appears when it’s least wanted and expected, whether it’s dropped on your designer sofa or appears in your newborn’s hair as she naps.

Read on to learn what causes babies to spit up, how to minimize it, and when you can finally bid adieu to your baby’s eruptions.

Experts define spit-up as the effortless regurgitation of small amounts of stomach contents. For babies, this is usually breast milk or formula. It’s incredibly common.

Your baby is more prone to spitting up than older children due to:

• An immature digestive system: You can mostly point to your baby’s digestive system as the culprit, specifically her lower esophageal sphincter (LES). This ring of muscle keeps food in her stomach and has yet to develop fully, making it easier for the contents of her stomach to make their way back up the esophagus. 1
• A small stomach: Because your baby has a small stomach, it’s easy to overfeed her and cause her to spit up. A good rule of thumb is to keep your baby’s daily formula intake to between 2 and 2.5 ounces for each pound of body weight. 2
• Swallowing air: Another common influence occurs when your baby swallows air while feeding. When this gas eventually creeps back up, it can bring milk or formula along for the ride. This is why you should also note your baby’s position and avoid sudden movements after feeding that could cause stomach contents to resurface.
• What you eat: While it’s less common, certain foods in your breastfeeding diet may also affect your baby’s spit-up. Try keeping a food diary to identify a pattern between what you eat and your baby’s spit-up frequency (but chat with your pediatrician before making any significant menu changes).

Get a professional opinion if you think your baby’s formula might be contributing to the spit-up. If there’s something like a milk protein or soy protein intolerance, your pediatrician might recommend a hydrolyzed formula for 2–4 weeks to see if there’s a difference. 3

What to know about gastroesophageal reflux disease in babies

Most of the time, your baby’s spit-up is a result of her immature physiology. That being said, certain conditions can make her spit up more often, the most notable being gastroesophageal reflux disease (GERD).

All babies have some degree of reflux due to their immature digestive systems, which usually clears up on its own as they get older.

However, you should seek medical attention if your baby shows more worrying signs of GERD, such as refusing to eat, crying or arching her back after feeding, or having difficulty gaining (or even losing) weight. 4

When will your baby stop spitting up?

Good news! The days of constant spit-up won’t last forever. For most babies, things will wind down when they’re around 6 months to 7 months old, coinciding with the ability to sit up independently and their digestive systems maturing. This is around when most babies start on solids, which are thicker and much harder to spit up.

By the time your baby is 12 months old, you should hopefully see an end to her constant spitting up. 4

You wouldn’t be the first mom to mistake normal spit-up for vomiting. Both involve releasing stomach contents, but there are several key differences. 5

The most obvious is that spit-up is typically gentle and only brings up small amounts (1–2 tablespoons) of stomach contents. This is why infants who spit up frequently are sometimes referred to as “happy spitters.”

Vomit is a bit more “explosive” in terms of larger quantity and force, even projectile. More extreme cases of vomiting could also signal pyloric stenosis, a condition where the stomach muscle thickens and keeps food from moving into the small intestine. 6

While spit-up is often unavoidable, you can minimize it by: 7

• Patting the gas out: If you’ve got a gassy baby on your hands, frequent burps will help release the trapped air during and after feedings. If your baby’s on the bottle, aim for a burp after every 1–2 ounces. For breastfeeding, burp when you switch breasts.
• Keeping her upright: Don’t be so quick to lay your baby down after a feeding. Let gravity help keep stomach contents down by holding her upright (at least 45 degrees) for at least 20 minutes or more. 4 With that said, for her safety, always place her flat on her back afterward to sleep, and never use inclined sleepers.
• Dressing her in loose clothing: Keep your little one’s wardrobe loose and avoid tight diapers that squeeze her tummy.
• Trying slow-flow nipples: These will keep your bottle-feeding baby from speedy, overzealous gulping.
• Chilling out after feeding: Avoid bouncing or vigorous play once your baby has eaten.

You can also try feeding your baby more often, but give her less during each nursing session to avoid overfeeding. However, the general consensus is that you should feed your baby as often as she demands, so get the all-clear from your doctor before trying this approach.

Some infants barely spit up, while others are seasoned pros. If your baby is gaining weight, feeding well, and doesn’t seem bothered by the spit-up, there’s probably nothing to worry about.

With that said, you should give your pediatrician a call if: 8

• Your baby spits up more than 1 or 2 tablespoons at a time 4
• Your baby consistently refuses to eat
• Spit-up is initially absent and starts after 6 months
• Your baby’s spit-up causes breathing difficulties or coughing
• Your baby shows signs of pain or discomfort related to reflux during or after feedings

Even if your baby doesn’t show these signs, don’t hesitate to chat with your doctor if you’re at all concerned.

While your baby’s spit-up may have left your favorite clothes looking a little more abstract than you’d like, take heart in knowing that it’s a normal part of her development.

Remember that your baby has her own unique digestive pace and tolerance. Trust your instincts, tune in to her cues, and chat with your doctor if you’re ever worried about your baby’s spit-up. You (and your washing machine) have this covered!