Hypermagnesemia may cause respiratory depression and decrease GI motility. Stools and bowel sounds are good evidence of GI mobility. This is so basic that it hardly ever fits the situation. A more useful guide is that most of the time infants need to gain weight. Less gain that that is suspicious for insufficient nutrition.
More gain is suspicious for fluid overload.
At birth, infants are supposed to lose water weight. For normal term infants the loss does not mean that they cannot begin to be well nourished soon. For ill or preterm infants, the limits of the immature gastroenteral function and fluid volume limits make immediate optimal nutrition more difficult in the first several days of life. Usually, TPN can be started by 2-4 days, and tiny, slowly advancing feeds can be started within a week. The schedule may be delayed by severe illness, electrolyte imbalances requiring frequent adjustments, and insults to the GI tract such as infection or asphyxia, potentially leading to NEC .