There is no evidence that the avoidance of eggs, peanuts, tree nuts, cow's milk or fish by a mother during pregnancy will prevent "Atopic Diseases" (e.g. asthma, eczema, food allergies, and allergic rhinitis) in a developing child.
There is no evidence that avoidance of the above noted foods by a breast-feeding mother will prevent the atopic conditions noted above for a nursing infant. If a nursing infant is known to be allergic to a specific food, then the nursing mother should not consume that food as components of the food will be transmitted via the breast milk and could cause a significant allergic reaction in the infant. If a nursing infant is at high risk for developing an atopic disease by virtue of having a parent or sibling with a significant atopic condition, it is prudent (but of unproven efficacy) for the mother to exclude those food items from her diet.
Infants should be exclusively breast fed and/or formula fed for at least the first 4-6 months of life. Babies that are primarily breast fed should be given 1 dropper-full of over-the-counter Poly-vi-sol Vitamins once a day. This is recommended because the transfer of vitamins A, D, and C from mother to baby is not sufficient for the baby's needs even if the mother has a good diet and is taking her own vitamins. Babies who are primarily formula fed do not need this supplement as all the major formulas have added vitamins in their formulation. For formula fed babies it is recommended to use fluoridated tap water or "nursery water" (distilled water with added fluoride) to dilute formula powder or concentrate. This is better than using "ready-to-feed" formulas which do not contain fluoride. Fluoride strengthens a baby's developing teeth and significantly decreases the incidence of cavities later in life.
Infants are considered at high risk for Atopic Disease if their parents or siblings have a documented Atopic Disease. These infants can at least be partially protected from developing the same problem by either exclusively breast feeding for the first 4-6 months and/or by feeding with extensively hydrolyzed hypoallergenic formulas such as Similac Alimentum Advance or Enfamil Nutramigen Lipil. These formulas are more effective than partially hydrolyzed formulas such as Good Start Supreme, Enfamil Gentle Ease, and Good Start Gentle Ease Soy which are less expensive and advertised as "hypoallergenic".
There is no evidence for the use of soy-based formulas as an allergy prevention.
There is no evidence that expanding a child's diet after 6 months of age to include fish, eggs, and peanut related products will increase the chances of developing an atopic disease. Baby foods can be introduced after 4-6 months of age. It is traditional to start with rice cereal first and then add single fruits, vegetables, and meats one at a time at 5-7 day intervals. The progression of the number of servings and increasing texture from pureed to "number 2 foods" to soft table foods can be undertaken at the rate that each individual baby seems to be capable of. As the amount of baby food increases, most babies will spontaneously take less breast milk or formula. If this does not occur, the child should be limited to a maximum of 24-32 ounces of formula per day.
Apple juice and other juices are often offered after 6 months. While they are a source of Vitamin C, they are otherwise a fairly non-nutritious source of calories. It is recommended to limit these to 4-6 ounces per day. Diluting them 50/50 with tap water is a good way to limit the amount of calories from the juice while also gaining the anti-cavity benefit of an increased fluoride intake from the water.
Cow's milk should be introduced only after 1 year of age. If cow's milk is introduced too early it can cause anemia and developmental delay due to microscopic blood loss in the stool because of an irritant effect of proteins in whole cow's milk. However, these proteins are not present in breast milk or infant formulas.