Constipated Newborns help!!

I found 5 abandoned babies...they havent pooped since 4 days!I massage theyre lil butts for like 3 mins,and with soap water,tried sticking a bit of soap in the bum,but nothing helps!
Can anyone tell me what can i give them?Some laxative or something?
Theyre like no more than a week.

They may not have had any food to become poop -- and at that age, it's usually kind of yellow mush, nothing formed, just keep dabbing their perineal area with moist damp cotton or some other non-irritating substance to make up for mamas tongue, and massaging them all over helps too, as mama would be washing them and massaging their bellies that way also..  Here are some videos that may help:

http://www.maddiesfund.org/Maddies_Institute/Videos/Orphaned_Kitten_Care_How_to.html