Let’s start with what you shouldn’t do. First: Don’t stockpile. More formula is being produced now than last year at this time.

Second: Don’t make your own formula. You can find “recipes” for formula online, with ingredients like cod liver oil and nutritional yeast. But they typically do not have the appropriate nutrient content. Although milk is the main ingredient in most formulas, milk alone is not a close substitute. Its carbohydrate content is too low, and it lacks many of the vitamins and minerals that are necessary for infants.

Third: Don’t stress too much about the brand. Beyond specialized formula, one formula is not too different from the next. Most are a mix of milk, lactose, oil (typically a combination of safflower, coconut, and soy), and whey protein. Soy formulas replace milk, lactose, and whey with corn and soy.