Opossums (or possums) are the only marsupial in North America. They have 13 nipples. Possums can have up to 25 babies but the average litter is 6-9. We will hopefully get to see how many babes this possum has soon! Possum babies stay in the mama’s pouch for 8 weeks and then they ride on their backs for about 4 weeks and become independant at around 12 weeks. Possums usually have one litter per year. WhatsThatShadow.com