In the first week, babies should have at least as many wet diapers as they are days old, in each 24 hours. They usually have at least one stool per day up to about 4 days, when we begin seeing more stools, and by which time the stool should have changed from the dark, tarry meconium stool to the yellow, very loose breastmilk stool. By a week, most babies are having at least two stools that are more than a stain on the diaper, per day. Some babies stool each time they feed, others do not, and some may skip a day. After a month to 6 weeks, many breastfed babies begin to space out their stools, and can go a week or longer without having a stool.
Most babies lose a little weight in their first few days.
As long as they wet and stool as expected, they do not need supplemental feeds. From their low point, most breastfed babies gain 4 to 8 ounces per week if latched well and feeding according to the AAP recommendations. It may be something very simple, or for your baby's well-being, formula supplementation may be appropriate while we sort out the difficulties. Supplementation should always be a medical decision, on the basis of insufficient wets, stools, or weight gain, not because the baby is fussy. If required, supplements can be given without causing problems, by using feeding methods other than bottles.