Babies born 20 days of age are usually recommended to breastfeed, how much formula milk to feed depends on the breast milk and the baby’s digestive tract to judge, such as can not breastfeed the baby, it is necessary to feed the formula milk, about 6 to 7 times a day, each time 100 to 120 ml. Babies of 20 days of age, belonging to the newborn, are usually recommended to breastfeed, the number of breastfeeding day and night about 6 to 7 times, day and night breastfeeding intervals are similar, about once every 3 hours, the latter half of the night can be a little longer, and the amount of breastfeeding each time is about 100 to 120 ml. For how many milliliters of formula milk for babies of this age group, it is necessary to combine with the adequacy of their breast milk and the baby’s digestive tract tolerance and other factors to make a comprehensive assessment of the decision, such as the mother’s milk is sufficient, the baby’s digestive tract tolerates well, and can meet the needs of weight growth, then there is no need to add additional formula milk. For those with insufficient breastmilk, breastfeeding should be carried out first each time, followed by supplemental formula feeding. If the amount of supplemental formula feeding can meet the development of the organism, with good weight gain, adequate sleep and good urine output, the amount is considered appropriate. It is recommended to consult a specialist for guidance on feeding if necessary.