Is a 12-month-old baby's stomach fully developed?

A 12-month-old baby's stomach has already developed maturely. The process of stomach development in babies mainly consists of three stages: the gastric development stage, the gastric digestion stage, and the gastric maturation stage. The gastric development stage is the initial phase of stomach development, lasting from birth to 3 months of age. During this period, the baby's stomach is not yet fully mature and digestive function is weak. The gastric digestion stage is the middle phase, spanning from 4 to 9 months of age, during which the baby's digestive function gradually strengthens. The gastric maturation stage is the final phase, occurring from 10 to 12 months of age, when the baby's digestive function becomes relatively mature.