Janmastami
Unlike us, Lord Krishna arrives in this world by His own sweet will.
As infants, we enter this world in a delivery room because we need to be delivered from the confines of our mother’s womb. Lord Krishna, the Supreme Personality of Godhead, comes here as an infant, too. But He has no need for a delivery. He arrives by His own sweet will, and His purpose is to deliver us. He plays the role of an endearing and dependent newborn, but He is complete with all of the powers of the Godhead.
King Kamsa heard the prophecy
According to a mystical prophecy, the eighth child born to Krishna’s parents, Vasudeva and Devaki, would defeat Kamsa, the cruel king of Mathura. This eighth child was none other than Lord Krishna. When King Kamsa heard the prophecy, he became determined to destroy Krishna. Kamsa locked up Krishna’s parents in a prison, and there Krishna’s mother gave birth to seven children, six of whom died by Kamsa's cruel hand.
Krishna entered this world through the heart of his father, Vasudeva, who had performed strong penances and austerities for thousands of years in his previous lifetimes. Vasudeva did this in order to achieve an intense meditation on the Lord by which He was able to attract Krishna to appear as his own son. Devaki, alongside her husband, had also engaged in long severe penances to attract the Lord. From Vasudeva’s heart Krishna was transferred to the womb of Devaki.