Newborns can sleep flat on their backs for two weeks, but be aware that it is generally not recommended to lie flat on your back immediately after breastfeeding. Newborns are usually able to lie down after birth, so a two-week-old can sleep flat on his or her back. However, it is generally not recommended to lie down directly after feeding, but to take the right side position after burping, then the left side position, and then the supine position after that, in order to avoid overflow of milk or choking and so on. Because the newborn’s stomach is horizontal, and the cardia is not yet well developed, so lying down immediately after eating is likely to cause spitting up, poor breathing, etc. However, as the child grows up, and the digestive system is gradually developed, you can extend the time of lying down to sleep. Therefore, newborns can sleep flat on their backs for two weeks, but it is not recommended to lie flat immediately after eating. Newborns sleep in a wide variety of positions and generally do not require special treatment, but it is still important to pay attention to the need to strengthen infant care to avoid accidents.