• Swallowing air when crying.

A baby who cries for a long time can swallow extra air, especially if the crying is intense (colic).

• Swallowing air when sucking.

When you feed your baby from a bottle, hold your baby almost upright in your arms, using skin-to-skin cuddling. And burp your baby when they’re finished eating.
A baby may swallow excess air during bottle-feeding when drinking too fast or if they are fed while lying down. Your baby is swallowing too fast when:

• They’re not taking a breath between swallows.
• Their eyes are opened wider than usual.
• Their nostrils are flaring.
• Their arms and legs are stiffening as they struggle to breathe and feed at the same time.
• Breastmilk or infant formula is leaking from the sides of their mouth.

Let your baby control the flow of milk and follow their feeding cues. If they drink too fast, tip the bottle down to slow their feed, or remove it. Your baby should not gasp, cough, or cry while bottle-feeding.
A baby may also swallow excess air if the nipple has holes that are too big. If you bottle-feed your baby, use nipples with holes large enough to drip cold formula at 1 drop each second.

• Position.

Gas may get trapped in a baby's belly when they are lying on their backs. Until their first birthday, babies should always sleep on their backs to reduce the risk of sudden infant death syndrome (SIDS). But when your baby is awake, you may help prevent or relieve some belly discomfort by holding your baby upright. Or you can give your baby some "tummy time" while you watch closely.

• Certain foods.

Giving certain foods, such as cow's milk or juice, to your baby may cause your baby to have excess gas. Some people have problems digesting milk protein or milk sugar (lactose intolerance). But these problems are very rare in babies.

If you think your baby may have this problem, it's not usually recommended that you switch formula or stop breastfeeding until your baby has been checked by a doctor.