My nephew is gaining very little weight and does not drink enough milk. he is over 4 months and weighs less than 5kg. what is the danger?

Doctor can check: All babies should grow, but they are all different sizes. That is why frequent check-ups during the first year of life are needed to see if any problems exist. The baby can just recheck with his pediatrician. For example, a baby born at 6 pounds normally weighs around 12 pounds at 5 months. However, a baby born at 9 pounds should be much heavier than 12 pounds by 5 months of age.