Why Babies Spit Up, According to Pediatricians

As a new or soon-to-be parent, you might be wondering: "What can be so hard about feeding a baby?" They only consume formula or breast milk, right? But feeding a newborn can be stressful as you learn your baby's hunger cues and get into a rhythm with breastfeeding or bottle feeding. And sometimes, it can even be a little anxiety-provoking, especially when babies spit up what looks like their entire feeding.

Rest assured, spitting up is completely normal for young babies, and it can happen for a few different reasons. Most babies who spit up generally still eat well and gain weight appropriately, but there are also some red flags to look out for and reach out to your pediatrician about. Ahead, we explain why babies spit up, how to help prevent it, and how much is too much.

The most common reason babies spit up is that they're being overfed. "Babies will feed until they spit up, so we have to be careful that we don't offer them too much and offer them the right amount for their age and tummy size," says Danelle Fisher, MD, FAAP, pediatrician and chief of pediatrics at Providence Saint John's Health Center in Santa Monica.

Most newborns eat every two to three hours and only take in one to two ounces at each feeding, gradually increasing to two to three ounces by the time they're two weeks old, according to HealthyChildren.org, created by the American Academy of Pediatrics. Every baby is different, but if they're spitting up, it's most likely a sign that they're full.

To prevent overfeeding, follow your baby's cues or try providing smaller feedings more regularly. Even if your baby spits up a large amount, they actually got more than what you think they need, Dr. Fisher says. If you're feeding with a bottle, Dr. Fisher recommends starting with a preemie nipple flow because it's slower than other nipple flows and allows your baby to pace themselves.

"If your baby starts fighting the bottle, you can always think about using the next-size-up nipple, just to make sure that you're giving the right amount and flow. And it's OK to switch back and forth between nipples. Sometimes you have to play around a little bit because babies don't talk to you. We're trying to guess what they need," she says.

Breastfed babies are less likely to be overfed because they're able to pace themselves when they nurse, says Elena Shea, MD, IBCLC, a pediatrician and certified lactation consultant. However, moms who have an oversupply or a fast letdown can overfeed their babies because the baby ends up consuming a large amount of milk in the first few minutes of nursing.

In this case, "mothers with a fast letdown can hand express milk prior to latching their baby, so that the baby avoids the letdown issue. Mothers with oversupply can work to moderate their supply. Despite the prevalent idea that oversupply is a good thing, it can have lots of consequences, including mastitis and clogged ducts," Dr. Shea says.

You can also try nursing in a reclined position, which is ideal for preventing spit up: "Mother lies back to about a 45-degree [angle] position and can then hold the baby in the traditional cradle hold or football hold. This position limits the effects of gravity in moving milk and makes the baby work a little harder to feed. It helps slow milk flow," Dr. Shea says.

The muscle tone in the esophagus, which is the tube that carries food and liquid from your throat to your stomach, is very loose in babies, Dr. Fisher says. So if they overeat, they spit it up.

"What happens is it's very easy to then have stuff in your stomach come back up. If you think of adult heartburn, it's the same physiologic thing in babies. Some babies have more tone than others and just have a worse time with reflux than other babies, so there are different patterns of spit up," she explains.

The connection between the esophagus and the stomach also tends to be immature in babies. "Instead of providing a sharp, band-like stricture, food contents can easily pass from the esophagus to the stomach as well as vice versa from the stomach back up through the esophagus. As infants begin to grow and meet their developmental milestones, such as sitting independently, standing, and walking, it's common for reflux to resolve on its own with the help of gravity," says Ronald Potocki, DO, a pediatrician at Orlando Health Arnold Palmer Hospital for Children. Sometimes babies may also spit up when they have increased abdominal pressure, such as while pooping or burping.

Babies can also spit up if they gulp down some air with milk, according to HealthyChildren.org. Because baby stomachs are small and can't hold a lot, air can fill it up quickly and cause gas or spit up.

One way you can help prevent spit up from reflux or gas is to keep them in an upright position 15 to 20 minutes after a feeding, Dr. Potocki says. This allows gravity to keep breastmilk or formula to stay in your baby's stomach. As mentioned above, you want to burp after every feeding to remove excess gas and prevent bloating, he adds.

Additionally, you can help remove gas by burping your baby before switching breasts or taking breaks during bottle feedings. If needed, you can also ask your pediatrician about some safe over-the-counter medications, like simethicone, to help break up gas, Dr. Shea says.

"Also, it is important to avoid any activities that could potentially increase abdominal pressure, which can worsen reflux, such as placing [the baby] in swings and car seats immediately after feeding," Dr. Potocki says.

Some spit up at most feedings is normal; it's more to note how the spit up is coming out as well as what it looks like. Generally, spit up should be the same color as breast milk or formula, and some curdling is also fine.

But spit up that is projectile — for example, hitting a wall on the opposite side of the room or splattering on the floor — should be addressed with your pediatrician. In addition, spit up that has some color to it, like a yellowish or greenish tinge, could be bile, Dr. Fisher says.

"If that happens, the parents should alert their pediatrician that the baby has unusual-colored spit up," she says. "You should also talk to your pediatrician if you see blood in spit up, although blood can be tricky. Some moms have very sore, cracked nipples that actually have a little bit of blood. So if the baby spits up, sometimes there could be some swallowed maternal blood. But if that's the case, you probably are just going to see a small amount. If you see a large amount, that's also a reason to alert your pediatrician."

Many parents may worry that their baby is spitting up too much and not taking in enough formula or breastmilk, but if your baby is peeing and pooping regularly, then they're getting enough food and are gaining weight. That said, if a baby spits up a lot and isn't peeing or pooping, that's a red flag that you should bring up with your pediatrician.

Many parents may suspect that their baby has an allergy if their baby spits up a lot and often, but spitting up alone isn't a sign of a food allergy or sensitivity. Babies who have a true allergy (most commonly, to cow's milk protein) will experience other symptoms such as poor weight gain, a rash or hives, dehydration, a sunken spot on the baby's head, and blood-tinged or mucousy stools, Dr. Potocki says. If that's the case, reach out to your pediatrician to get a full evaluation.

However, some babies who nurse may have a sensitivity to certain foods, most commonly milk and soy. If your baby seems very uncomfortable, speak to your pediatrician about possibly doing an elimination diet. If you're breastfeeding, it's important to consult your pediatrician before making any changes to your diet to prevent a nutritional deficiency, Dr. Shea says. For example, removing dairy from your diet can lead to calcium and vitamin D deficiency. Similarly, parents should avoid changing their baby's formula without first consulting their doctor to ensure they're getting enough of the right nutrients.

There's quite a range for when babies outgrow spitting up — anywhere from four weeks to six months. According to the Mayo Clinic, most babies stop spitting up by their first birthday.

Some babies might outgrow it faster than others, but as your baby gets older with each passing month, the amount and frequency of spit up should gradually decrease over time, Dr. Fisher says.