There is a certain period that newborns go through of excreting everyday because their system is getting rid of any myconeum. You should have been given a list at the hospital of what to look for (eg. the first day or so its this dark gooky stuff, but then turns into a more runny yellow mess). But, once that is out of their system, not going daily is quite normal. My daughter was breast fed and when she went 5 days without going everyone (not the doctor) freaked out. The doctor thought their might be some constipation so he had me try to give her pear juice--she wouldn't take that. So, I drank it to get it to her indirectly. Then I stopped. His concern was constipation, but there were no signs--no discomfort, no straining, no blowouts even. She was simply using everything I gave her. That's normal and wonderful. Formula has stuff in it that she can't make use of, that's why formula fed babies go more often. Check with your doctor about when all the initial myconeum ridding is finished, and if that's over, and your son is not straining or in discomfort, it just means that he is a healthy baby getting the best stuff anyone can make.