In the epic The Mahabharata, we get examples of the Pandavas. The Pandavas, Kunti and Madri were the queens of King Pandu of Hastinapura. Pandu once accidentally killed a sage and his wife. As he died, the sage cursed Pandu that he would be unable to have children by his queens.
However, Kunti had a prior boon from Sage Durvasa that she could have sons by any god that she prays to through immaculate conception. God of Dharma granted Yudhishthira, who was thus the embodiment of Dharma. Vayu, the wind God, granted Bhima, the epitome of physical prowess. Indra’s grace resulted in the birth of Arjuna, the consummate warrior. Kunti shared the boon with Madri, to whom were born Nakula and Sahadeva, the handsome twins, due to the grace of the Asvins. The story of the birth of the Pandavas is a perfect example of the unlimited benefits and the power of prayer and rituals during pregnancy.