Baby Boy of 4 months weighs 6.2 kgs?

after 4 months, fed babies slow their weight gain. your milk is just fine, your baby is just using energy for things other than putting on more weight (like playing). your milk is still giving him everything he needs, and will continue to do so as long as you feed on demand. you can expect the rate of weight gain to decrease even more at about 6 months, again, this is normal and perfectly healthy. if you are worried, you can look at his weight on a growth chart made using fed babies, like the one on Kellymom.com