According to Baidu Encyclopedia, the pocket on the kangaroo's stomach is used by the kangaroo mother to feed the baby kangaroo, which is called the nursing bag; Kangaroos have no placenta, so embryos can't mature in their mothers. Pregnancy is only 33-40 days. The premature kangaroo baby is less than two centimeters long and weighs less than one gram, which is equivalent to the size of a human finger. It can only stay in its mother's pouch and live on breast milk.

Kangaroo mother's pouch is equivalent to the second uterus, which provides a safe and comfortable environment for the growth of kangaroo. This pouch is amazing, and it will get bigger as the child grows up. When the kangaroo mother bends down, she can tighten the pouch by contracting her muscles, so that the baby kangaroo will not fall out of the pouch. Kangaroos will grow from a flower to the size of a cat as long as they stay in their mother's stomach for 8 months.