I BF my son for 3.5 years and then he weaned himself once I was into the second trimester with my daughter. Now that my daughter is born I have plenty of milk and I thought I will give some pumped BM to my son to boost his immune system. He is going to preschool and gets sick a lot during winter so the BM should protect him (and the baby at home who will have to be exposed to the germs if her brother gets sick). It's been about a month that I started giving my son about 4oz of EBM a day. Yesterday I realized he looked really big and measured his height and I was shocked to see he grew an inch in a month!!! He is 4 so he is not at the 5 year growth spurt point yet. Here is my question: we know that BM contains lots of age-appropriate growth hormones. Is it possible that the BM designed for a 6 week old is not good for a 4 year old? Too much growth hormones? Am I doing harm more than good?