My seven week old baby poops once every other day, is this normal?

Other symptoms?: If our baby is eating well, making a good number of wet diapers, is not vomiting and is gaining weight appropriately, that is the best indication. Babies on formula poop more frequently (can be multiple times per day) versus breastfed infants can sometimes go a week in between poops and that is ok too.

Yes and no: Breast fed babies in general have a bm with all feeds (4-5x daily) formula fed babies once every 2-3 days and are more constipated

Yes: As long as stools are soft/mushy/liquidy when the baby does poop, the pattern you describe is perfectly normal. Some babies are just so efficient at digesting their mom;s milk that they may not make a lot of waste product (poop), so dont stool as often. Many breast fed babies give little runny skid marks with each feed. Consistency of the poop matters, not frequency.