Agreed with subha 30-60ml in one go would be sufficient depending on birth weight. If you can express 50ml in one month, believe you me! you would be able to express 90 to 100 till your baby reach 3rd month. follow same healthy diet mentioned by babychakra veteran experts.

don't worry that you are able to pump 40-50ml in a single sitting. initially it'll be like that only. gradually you'll see the increase in supply. drink warm water or milk and gently massage your breasts before pumping. this helps a lot.

oh!! ok, if formula then don't give 90ml at a stretch. it may be heavy for the 1month old baby. give 30ml first, burp your baby, give some time and again if baby cries then give remaining. 1 month baby require just some 40 to 50 ml I hope. that too formula feed is bit heavy to digest so gradually increase the quantity

thanks subha I am not able to produce 90ml of expressed milk. maximum is only 40 to 50 ml in one go that too take more then half now hour. I was talking abt formula feed in my question.

90ml of expressed breastmilk is fine. since your baby is just 1month old try to minimise the quantity of formula and increase the quantity of your milk