Answer: If he is fully breastfed and developing well, then try not to worry. Babies generally double their birth weight by 4-6 months and triple it by 12 months. Gender, environment, feeding/nutrition and genetics all influence growth. But every baby is an individual and will gain weight in their own unique way. What often happens with breastfed babies is that they put on alot of weight in the first few months and then plateau out for a couple of months. He may be one of those babies. If you’ve had alot of breast milk and he’s been feeding alot then obviously, this will have influenced his weight gain.
He is higher than the 97th percentile currently for his weight but what about his head circumference and his length. Are these consistent with the same growth pattern? Most medical guidance on excessive weight gain at this age for breastfed babies is not to worry. There are some (very) rare conditions where babies are very large and gain weight very quickly though there are usually other concerns which are apparent.
Were you or his dad very large as babies? Did you have gestational diabetes?
Without knowing more information I cannot advice you further. But honestly, if you’re worried and it sounds like you are, then you could request a referral to see a paediatrician, either through your GP privately or at your local children’s hospital. Think about his feeding pattern, if you feel he’s feeding excessively then perhaps you’d want to think about cutting back on his feeds. At four months of age, around 5-6 breastfeeds in a 24 hour period is reasonable if the mother has a good supply and the baby is feeding effectively. Avoid starting solids too early, this is likely to add to his weight and size. Six months is the current recommendation.
Cheers
Jane