Just had my 13 week old DS weighed and he is now on the 25th centile at 12lb 12oz having been born at 9lbs (just under 91st centile). He has slipped gradually - didn't gain above birthweight until 4 weeks then tracked 50th between 4 and 8 weeks then started to slide.
I know breastfed babies are meant to grow in spurts, but what seems to happen is that his spurts just about keep him on the line he is on and then his average weeks see him drop.
HV is just starting to question his weight gain now, albeit gently - so I don't feel pressurised to do anything yet but at what point, if at all, should I worry? Are there health problems associated with babies not gaining weight very quickly and dropping down the centiles like this? If not, why is weight gain considered so important if there is no problem with slow gain like this?
FWIW, he is a tall slim baby (maintained 75th centile for height while dropping so much on weight) and is very happy, and I think reaching most of his milestones (rolls, giggles, sleeps well etc.). So I'm okay at the moment and not planning a drastic switch to formula or anything like that but I just want to understand if this slow weight gain could actually indicate an underlying problem and/or be the cause of future health problems, or whether it is not really anything to worry about other than something to argue with HVs over.
Also I'm not actually planning to have him weighed more frequently than monthly from now on, unless I am worried. Does that seem a good idea, or should I be getting him weighed more frequently given this continual slide?