For a 17-day-old newborn, 3 to 5 stools per day is normal if he or she is breastfed; 1 to 2 stools per day is normal for formula feeding, but there are individual differences. 1. Breastfeeding: Breastmilk will lead to an increase in the number of bowel movements, and it is normal to have 3-5 bowel movements per day. The main reasons are: breast milk contains prostaglandins that can promote intestinal peristalsis, leading to more frequent stools; at the same time, high lactose content, which can easily lead to lactose intolerance and other symptoms; at the same time, some of the breast milk has a high fat content, which can easily lead to steatorrhea. 2. Formula feeding: Formula feeding 1~2 times a day is normal. Lactose content in milk powder is low, and casein breast milk in milk powder is high, which also triggers low stool frequency. To determine whether the stool is normal, in addition to the frequency, but also depends on the nature of the stool and whether there are other accompanying symptoms. If your 17-day-old baby has abnormal stool frequency or other problems such as mucus, pus or blood, you should seek medical attention from your neonatologist to find out the cause of the problem and treat it aggressively.