Punarapi Jananam, Punarapi Maranam - says Shri Adi Shankaracharya. We keep on going through cycle of birth - growth - oldage and death. This is cycle of suffering. Punarapi janani Jathare shayanam - in the womb of mother.
This is called cycle of transmigration. This process continues until we evolve spiritually. Evolve spiritually or revolve in the cycle of birth and death - this seems to be the choice.
The trapping in cycle of birth and death happens due to ignorance of our higher Reality. Due to wrong understanding of the nature of reality ( Inner/Outer/Higher), this process continues.
One who evolves spiritually - called Jivanmukta gets out of this cycle.