Why do infant throw up after feed especially through the nose?

Infants may vomit after feeding due to several factors, including immature digestive systems, overfeeding, or swallowing air while feeding. Their lower esophageal sphincter is still developing, which can lead to reflux, causing milk to come back up. When they vomit, the force can sometimes push the milk out through the nose, as the nasal passages are connected to the throat. This is usually normal and tends to improve as the infant grows.