William J. Klish, M.D., is Professor of Pediatrics, Head of Pediatric Gastroenterology at Baylor College of Medicine and Chief of the Nutrition and Gastroenterology Department at Texas Children's Hospital in Houston. Dr. Klish has served as chair of the Committee on Nutrition of the American Academy of Pediatrics.

Q: My 6-week-old seems to really be bothered by gas. Should I consider changing her formula?

A: A formula change will probably not help. The most frequent cause of gas in babies is swallowing air, either during feeding or periods of fussiness. Many babies are aggressive feeders who gulp their formula, which increases the intake of air. If you notice your infant doing this, try feeding her in a quiet environment, help slow her pace by interrupting frequently, and be sure to burp her often.

Also check the opening of the nipple. If it's too big, your baby will be flooded with formula and tend to take in air. If the nipple is too small, too much air can also be ingested, since a baby needs to suck harder to get the formula. Lactose intolerance can also cause gas, but is extremely rare in infants. This condition is almost always associated with diarrheal stools described as foamy because they are mixed with gas.