New born baby not putting much weight on...?

Because he's fed he won't whack on weight like a bottle-fed baby (the growth charts are based on bottle fed babies BTW) but this isn't a bad thing! If the health visitor isn't concerned and so long as he's getting wet and dirty nappies and looks okay- responding normally IE waking and crying for food, and his fontanelle isn't sunken, he's fine. If she is concerned then a visit to the GP isn't OTT :)