This is an excellent and very common question from new mothers these days, Elizabeth. The American Academy of Pediatrics recently changed their recommendations about starting solid food from 4 months to 6 months. I am pleased to hear your pediatrician has taken these recommendations seriously.
Even though we say a baby is “full term” after 40 weeks gestation, some of the infant organs are still maturing throughout the first year, particularly the liver and kidneys. Certain digestive enzymes may also be in shorter supply for the first few months. While babies have grown satisfactorily for many years with earlier introduction of cereals and other solids, they don’t eat quantities that make a positive impact on the baby’s diet.
More importantly, giving a baby solids too early can cause then to take less breast milk or formula, which still contains all of the calories, vitamins and minerals the baby needs to grow appropriately. If a baby can’t easily digest a certain food, his body will use more energy to try and digest rather than use those calories toward growth. Furthermore, younger babies are more susceptible to allergic reactions.
The information given to your mother and mother-in-law was appropriate for their time, but new research has shown that it is not necessary or preferable to start solid feeding before 6 months of age.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.