Dr. Greene's Answer
There are many types of food intolerances, and some of them can trigger eczema and cause poor weight gain.
Both wheat and dairy commonly cause allergies and worsening eczema in babies. Many of those who are allergic to dairy are also allergic to soy.
Your baby needs a good source of protein, calories, fat, and other nutrients. For infants, breastmilk or formula is usually the best way to get these things. While breastmilk is preferred over formula, some babies with severe or multiple allergies may need a hypoallergenic formula because allergic components of food can pass from mother to child through breastmilk.
Hypoallergenic formulas include protein hydrolysate formulas, such as Nutramigen and Alimentum. Some kids with severe allergies need to be on an even more elemental formula, such as Neocate, but you will want to work with your pediatrician before making that choice.
There is now a blood test for diagnosing celiac, called the serum IgA-endomysial antibody test. It is possible that this condition or eczema could be linked to low weight gain, but keep in mind that 10 percent of healthy kids are at the 10th percentile so it could also be the size she is built to be.