A: Congratulations on your choice to breastfeed exclusively for the past four months. Since you’re planning to continue breastfeeding when you’re at work, you should know that your baby will continue to experience the benefits for many years to come. By the way, many women find themselves unable to pump large amounts of milk, so this is not a unique problem. I applaud you for trying to provide expressed breast milk when you’re away from your baby.

Regarding your question, there are really only two kinds of formula: cow’s milk and soy. The “recipes” for each brand are almost identical, so choosing between brands should not be difficult.

First, decide whether you want to use a milk-based or soy formula. There are pros and cons to both. Cow’s milk proteins can be allergenic to some babies, and the lactose in these formulas can cause a lactose sensitivity that can cause lots of gas and tummy aches. Soy formulas don’t use lactose as a carbohydrate, and obviously the proteins are different. But if there are any nut allergies in the family, it could trigger an allergic reaction. There is also concern, and controversy, regarding the early introduction of plant estrogens naturally found in soy formula, but the digestion of soy formula is easier on the breastfed baby.

Whether to use milk-based or soy formula is a choice you should discuss with the pediatrician, but what brand you choose is your call. There is no scientific basis for picking one brand over another. Most commercial formulas have DHA and ARA, the essential fatty acids needed for vision and brain growth. These naturally occur in breast milk, so your baby will continue to receive this wonderful gift from you.

I recommend buying the least expensive brand of formula, using coupons and store sales to lower your cost. Don’t be too concerned about staying with a single brand.