My 18-month-old child has started to hold onto his food in his mouth.

It is important to be vigilant when a young child starts holding food in their mouth as it can be a choking hazard if they lie down with food still in their mouth. It is recommended to ensure the child's mouth is empty before bedtime or when they finish eating. One way to teach them proper chewing habits is to only give them one portion at a time and not give them more until they have emptied their mouth. This way, they will eventually learn to chew and swallow properly.