Over the past few years, the American Academy of Pediatrics and other international pediatric leaders have changed their recommendations for beginning solids from four months to six months. The following immunological and developmental considerations prompted this change in recommendation[i]:
A baby’s intestines are still developing.
During early infancy the intestines secret only a small amount of IgA, an immunoglobulin protein that coats and protects the lining of the intestines. Fortunately, breast milk contains a lot of IgA that offers this protection while the intestines are developing. Between four and seven months the intestines go through a developmental process called “Closure”. This process causes the intestines to be more selective about what is allowed to pass through. If breast milk is reduced and solids are added before this closure occurs, the baby’s immune system can be triggered to begin an inflammatory, allergic-type response to proteins that leak through the intestine. It is now believed that this process can initiate life-long allergies and asthma and may be a component of a child’s later developing autoimmune illnesses such as diabetes.
Babies less than four months have the tongue-thrust reflex.
This reflex protects the baby from choking. When food is placed on the tongue, the tongue pushes the food out rather than drawing it in.
The baby’s swallowing mechanism is still immature.
Between four and six months babies develop the ability to move food from the front of the mouth, to the side for chewing, and then to the back of the throat for swallowing.
By six months most babies have developed the ability to sit.
Being upright obviously facilitates the eating of solids and a baby’s ability to participate actively in the process.
Older babies love to imitate their loved ones.
By six months a baby may grab mother’s spoon or the cracker from a sibling’s hand. This imitating of behavior not only increases a child's ability to self-feed, but also contributes to the baby’s developing cognitive, social and intellectual skills.