By day 3 your baby's stomach is the size of a ping pong ball. Compared to a shooter marble, bigger, but still something you and your body can handle! By day 10 your baby's stomach is the size an extra large chicken egg.

When do babies tummies get bigger?

10 days to two weeks

The expansion of your baby's stomach will have slowed a little now. But by the time your baby is two weeks old, his stomach will be roughly the size of a large hen's egg.

Do babies normally have big bellies?

On average, babies pass gas about 13 to 21 times every day. A bloated baby belly due to gas is therefore quite common and usually doesn't require any special treatments. Gas is particularly common in infants between one and four months, as their digestive systems are still developing.