Also, the WHO has just issued new guidelines on what constitues a "normal" weight and height for all children from newborns to 5 years old. They have based it on samples of children from all over the world (not just the U.S. as the previous chart) who have been EXCLUSIVELY breastfed for the first 6 months. So what normally would have constituted an 'underweight' child, (usually an exclusively breastfed one) is really probably at a normal weight.

The same thing happened to me, after 6 weeks, I was told that my baby was very underweight and strongly encouraged to give her formula. When I was only giving her 2 bottles a day, I was told "not to be so stingy" and to give her more bottles, much to my dismay. I don't think this is advice peds. would give in countries such as my native Canada.