What causes vomiting? A baby\’s life is full of surprises, one of which is spitting up milk. When your baby starts spitting up milk, it can make you feel worried and helpless. Here we will discuss several reasons that may cause your baby to spit up milk. Underdeveloped Digestive System It takes a while for a baby\’s digestive system to fully develop after birth. During this period, your baby may spit up milk, which is very normal. This may be more common especially after your baby drinks breast milk or formula for the first time. Babies have very small stomachs and limited digestive capacity, which means they may eat too much