Dr. David Barker, an internist at Oregon Health and Science University, examined medical records of more than 8,000 people in Finland Those who developed heart disease were small newborns, thin at two, but by 11 had gained enough weight to catch up with their peers.
Small thin babies are born with fewer muscle cells. If they gain weight before two, barker says they can add more muscle, but after two they're not making any more muscle, they're just storing fat.
The American Academy of Pediatrics recommends breastfeeding for the first year and iron supplements for some underweight babies.
If you think your baby is gaining too much or too little weight talk to your pediatrician.