When Brodie was 5w6d old I went to the pediatrician with him. I wasn't planning on going in, it wasn't a scheduled appointment or anything. Brodie just hadn't pooped...in a week...
I walked in for an appointment because the nurse had told me if he hadn't pooped in a week that they were going to give him a suppository. :( My poor guy! They weighed him when I got there and he weighed 9lb 12oz (a gain of 1lb 2oz in exactly 3 weeks). Then, the doctor came in to examine him. He said that his belly was nice and soft, he didn't seem uncomfortable (he was smiling at the doctor the entire time), and that he was gaining weight so he was ok. He told me to give him 2oz of prune juice with 2 oz of water in a bottle 1-2x a day for 5-7days to help with get the poo moving. He wasn't constipated, because he is breastfed, but he still said he likes to see breastfed babies pooping at least once every 5 days.
I felt very wary about giving my baby prune juice, but went and bought it anyway. I called my mom to ask her advice and voice my concerns. She suggested I try giving him an oz or 2 of water first to see if that helped. So, I filled a bottle with 2oz of water and gave Nick the bottle to feed him (it was his first bottle and I didn't want him confusing the food I give him with the bottle). Well, he got less than 1/2 an oz of water "down." By down I mean he gagged on some water, drooled a lot out the sides of his mouth, and sucked down a little bit. After he was done with 1/2 an oz he immediately starting pooping, EVERYWHERE. Nick was holding him and he pooped all over Nick, himself, Nick's office chair, and was dripping a puddle of poo on the floor. I bet he lost 1/2 a pound from it! We were so happy we didn't have to give him prune juice! Daddy and Brodie went right into the shower to clean up and he was fine from there on out.
Here is a picture of the puddle of poo (that's not including what was on the chair, Nick, Brodie, or in Brodie's diaper). It was pretty epic!