when the haemoglobin of the child is less you have to give iron rich food to the child. the include green leafy vegetables along with dates and lentils that is different types of dal. fruits like apple banana. you can give jaggery in every food and also make food of the child in iron utensils.
when you are add lemon that is rich in
vitamin c to the diet which contains iron it helps in greater absorption of iron.
your doctor will tell which iron supplement needs to be given to the child and usually we recommended it for at least 3 months for improvement in haemoglobin level