Even though a female Virginia opossum gives birth to 4-25 young after a 12-13-day gestation, she generally only has 13 mammae, some of which may be nonfunctional.
After an extremely short gestation period of 12 to 13 days, 4 to 25 altricial “honey bee-sized” Virginia opossum young are born.
Even though female opossums can have up to 25 offspring, they generally only have 10-17 teats, but 13 mammae is the most common, some of which may even be nonfunctional. This is because only 8 of the 4 to 25 young will survive to the mother’s pouch. Once there, the young will remain attached to the mammae for approximately 50 to 70 days.
Sources: (Burnie, Wilson, & Clutton-Brock, 2001; Christiansen, 2006; Feldhamer, Drickamer, Vessey, Merritt, & Krajewski, 2007; Hoffmeister, 2002; Holmes, 1992, May; Hossler, McAninch, & Harder, 1994; McManus, 1974; O’Connell, 2006; Rademaker & Cerqueira, 2006; Siciliano, 2013; Wilemon, 2008)