The amount of milk a 17-day-old baby eats varies from person to person, with normal full-term newborns receiving between 60-90ml of milk. In case of preterm babies, it has to do with the gestational age and weight at birth. Formula-fed newborns should be fed with water once between formula feedings, while 80%-90% of breast milk is mainly water, so no additional water is needed. Although the amount of milk for newborns varies from person to person, the weight gain is objective, and it is normal for newborns to gain between 10-30g per day, indicating proper feeding and a weight gain of more than 600g per month.