Devaki had the greatest fortune of giving birth to Sri Krishna. But before this divine event she had to undergo several hardships – spent several years in jail; see her six new born sons getting killed at the hands of Kamsa. Devaki had to undergo all these sufferings as a result of curse.
Legend has it that Devaki in her previous birth was Aditi, the wife of Sage Kashyapa. The Sage also had another wife Diti.
Aditi became pregnant and gave birth to Indra. Diti too was blessed by Sage Kashyapa that she too will give birth to a brilliant son.
Aditi did not want anyone greater than Indra so she hatched a plan with Indra to kill the son of Diti in the womb itself.
For this evil purpose, Indra took became small as a microorganism and entered the womb of Diti and killed the baby in the womb.
Diti who came to know about the reason for the sudden abortion, cursed Indra that He will never be the ruler of three worlds. She cursed Aditi to be born on earth and spend time in jail and see her sons getting killed.
Sage Kashyapa who came to know about the incident consoled Diti and said that her sons will also become Devas (demigods).
He also said that her curse will be fulfilled in the Dwapara Yuga.
In Dwapar Yuga, Aditi was born as Devaki and she had to spent time in jail and see her sons getting killed.
Due to an earlier curse from Brahma, Sage Kashyapa was born as Vasudeva.
Diti was born as Rohini – the mother of Balrama.