Kamsa intended to kill his cousin Devaki, fearing the prophecy that her eighth child was fated to kill him. Vasudeva managed to save his wife's life by promising Kamsa that he would deliver all their children to the latter. Kamsa accepted this proposition and spared Devaki because she herself was not a threat to him. In the confines of the prison, Devaki repeatedly conceived and Kamsa cruelly murdered the first six children. Before the seventh child was born,
Vishnu ordered the goddess
Yogamaya to transfer the seventh child of Devaki into the womb of
Rohini. This child would be raised by his surrogate mother, Rohini, and named
Balarama, Krishna's elder brother.
Yogamaya was tasked to be born as the daughter of Yashoda. Immediately preceding the birth of Krishna, the goddess rendered the guards of Kamsa unconscious. When Krishna was born to Devaki, heeding the deity's instructions, Vasudeva carried the infant to Nanda and Yashoda's house, swapping him with their infant daughter, Yogamaya. Presuming the infant to be Devaki's eighth child, Kamsa prepared to murder her, but the girl slipped out of his hands. Assuming her true form, Yogamaya proclaimed to Kamsa, "The eighth child, who shall kill you, has been born. He is in Gokula!" == Death ==