<s>[INST] our prematured baby when born was 2 kg and now she is 65 days old and 4 kg and we are feeding her pre nan since mothers milk is not sufficient as per the advice of doctor, now can we shift to nan 1, what is the better option pre nana or nan 1 or nan pro 1. please suggest [/INST] Hello, In case of premature babies it is recommended to continue with Pre Nan (or other types of artificial baby milk) until the baby is 4 months, in order for the baby to gain weight faster. Then, you can start Nan1 until 6 months old, and then you can change to Nan 2. Your baby girl is about two months old and about 4 kg, which is lower than babies born on term. If you consult with World Health Organization growth charts with the data of your baby (2 months old and 4 kilograms) then she is under weight (she should weight about 5 kilograms at this age). Therefore, you should continue Pre Nan for at least 2 other months in order to help your baby and give her best opportunities to catch up the growth pace of non-premature babies. Hope I have answered your query. Let me know if I can assist you further. </s>