It should also be noted that kangaroos have the ability to suspend the development of the embryo whilst another joey is still in the pouch, so they can be in a state of continuous pregnancy. The musky rat kangaroo has a gestation period of 19 days, whilst the red kangaroo has a gestation period of about 33 days.Most other kangaroo species have a gestation period of 31-36 days.Most of the development of the joey occurs in the pouch rather than in the womb. Young musky rat kangaroo joeys spend about 21 weeks in the pouch, while red kangaroo joeys spend an average of 9 months in the pouch.However, in reality, pregnancy length may differ.ost of the development of the joey occurs in the pouch rather than in the womb. Young musky rat kangaroo joeys spend about 21 weeks in the pouch, while red kangaroo joeys spend an average of 9 months in the pouch. However, in reality, pregnancy length may differ.