Why Do Newborn Babies Spit Up Milk?

The first few weeks post birth are like getting your dream jump, only to realize it’s to be a janitor – with the added fear of constantly thinking you’re doing something wrong. Whether you’re a new mom or a pro who knows babies spit more often than they smile, you’re bound to get worried when you think you’re washing more milk stained burpees than usual. To allay your concerns, we’ve rounded up some of the biggest reasons infants spit up their milk – in ascending order of seriousness.

Why do Newborn Babies Spit Up Milk?

  • They have small stomachs: as tiny as infants are, adults don’t really realize how teeny tiny their stomachs really are. At birth, a baby’s stomach is literally the size of a cherry. After some days, it progresses to the size of a walnut. By the 4th month, your baby’s stomach should be the size as a golf ball. The point is, there’s only so much milk that cherries and golf balls can hold before they overflow. It’s because of their small bellies that babies need to feed more often – as many as 8 times a day during the first 3 weeks of birth. Stuffing them full in one seating will only make them fussy, so they’ll spill some of the excesses out. Doctors recommend that you pace your feeding. Spend 10 to 15 minutes slowly feeding your baby instead of rushing them in 2 minutes. Note that even when it seems like your baby’s spitting up a lot of milk, it’s actually not that much. Plus, the whole experience isn’t even painful for your baby.
  • Excess Supply of Milk: heavy breast milk flow can cause infants to gulp and gag on milk, triggering lengthy coughing and spitting sessions. Because you can’t control how fast your milk flows, consider expressing into a bottle, then feeding your baby from the bottle instead of directly from your breast. Make sure you get a nipple with a moderate enough hole; not too big that it mimics your overflowing breast, and not too small that it frustrates your baby.
  • Excessive Movements During or After Feeding: the digestive system of an infant isn’t as developed as an adult’s. The digestive system has a ring shaped valve in the esophagus that becomes loose when food needs to pass through to the small intestine and tightens ups afterwards to prevent that food from coming back up. In adults, the muscles responsible for this KNOW their job, because they’ve been doing it for a while. It’s why an adult can eat, immediately get on a roller coaster, feel nauseous, but not throw up. In babies, the sphincter is perpetually loose. Even when it contracts to keep milk from moving upwards, the pressure from any type of jostling will force the content back out. You can’t do anything about the sphincter, it’ll grow when it’ll grow. However, you can keep the baby still during and after feeding. For at least 30 minutes, things should be calm, no bouncy chairs or tossing in the air.
  • Wearing too tight clothes: if you have one of those “too big for my age” babies, you’re going to have to eyeball their correct sizes most of the time. Tight clothes or diapers constrict the abdomen and can cause ingested milk to flow back up. It’s better to wear too big clothes than too small ones.
  • Gulping air: you can’t convince a baby who has recently moved from cherry to walnut sized stomachs that their meal won’t run away. Hungry babies are frantic babies. So frantic they guzzle down milk with lots of air. Air belongs in the lungs, not in the bowels with fluids. If not expelled immediately after feeding, your baby can become constipated. While trying to expel the offending gas through their mouths, some milk follows. If there’s stomach acid in the milk, your baby would experience acid reflux. If your baby gets fussy afterwards, they may be experiencing a heart burn, and are in need of medication. To keep this from happening, conventional wisdom states that you pat your baby on their backs until they let out a burp.
  • Allergy: the most likely offender is cow’s milk in baby’s formula. But if mom changes her diet, or is on a new medication, your baby could react to it. You’d need to consume a lot for it to actually affect your breast milk. Additionally, when babies catch a cold, they’re more likely to spit up milk. If you use formula, try buying those without cow milk, but if you’re breast feeding exclusively, stick to a regular diet. Some doctors say an early cold strengthens the immune system, but you should check with your pediatrician if you’re worried.
  • Pyloric Stenosis: we saved the worst, and the rarest, for last. Sometimes the sphincter – responsible for relaxing to let food from the stomach into the intestine, and constricting to prevent food from going back up – thickens and gets too tight for food to pass through to the intestine. Whatever’s left in the stomach will get regurgitated back, spilling from your baby’s mouth. In most cases, the baby will become dehydrated, and will begin to lose weight. This is a very serious medical condition that needs to be treated with surgery, so contact your pediatrician if you notice these symptoms.


Can I Breastfeed Even When I’m Sick?

Generally? Yes. Most illnesses aren’t harmful to breastfeeding babies because your body produces antibodies to fight diseases. These antibodies help protect your baby as well. Only in rare cases, like with HIV, would you need to stop and see a doctor.

Do Breastfed Babies Need Extra Vitamins?

Just vitamin D. However, mothers who expose themselves to sunlight can pass this vitamin to their babies, without using supplements.

How Can I Stop My Baby From Spitting Up Milk?

Keep all feeding sessions calm for about 20 minutes, burp them after each meal, don’t overfeed them, control the flow of milk they get (switch from breast to bottle if you have to), and keep all diets healthy.

Is it Normal For Babies to Spit Milk After Feeding?

Is water wet? Yes. Most babies spit milk after breast feeding. Mostly painless. You should only worry if the spit is colorful or your baby starts losing weight as a result.