The heaviest totally breastfed baby I ever saw weighed 27 lbs. at 4 months
of age- he was enormous. I had visited the mom postpartum as a PHN (baby
was 10 lbs. at birth) and next saw him at a LLL meeting when he was 4
months. This was the mom's 2nd child and she was a well-informed person
who was breastfeeding ad lib. She had trouble finding diapers wide enough
for her baby and finding clothing big enough for him. She was being
followed by an IBCLC who was also in contact with the paediatrician. Both
felt the baby was gaining at his own pace because mom was feeding
according to baby's need and doing everything right. Also, apparently ,
the mom gained this way when she was a baby. I remember seeing mother and
baby again when he was a year old and he only weighed 29 lbs- he'd gained
only 2-3 lbs. in 6 months- he put all his weight on early.

Interestingly, this dyad was a case study in a workshop I attended a few
years later, given by the IBCLC who followed her (I just checked notes
from that workshop).

I have been able to keep an eye on this boy over the years, because he has
ended up on some of the same sports teams as my son, and he is totally
normal in size- he may be slightly taller than the norm, but certainly not
fat.

Maureen Kennedy PHN IBCLC