Krishna was born as the eighth child because, when Kamsa was taking Devaki and Vasudeva on the chariot, by becoming the charioteer himself, an ashareera vaani was heard, “O Foolish Kamsa! The sister whose chariot you are driving, her eighth son will be the death of yours.” So, that’s why Krishna came as the eighth child. This was just a superficial reason. There was a sequence of curses and karmas that were to be fulfilled before the appearance of Krishna.
After this ashareeravaani, Kamsa was about to kill Devaki, and that too on the day of her marriage to Vasudeva. Vasudeva calmed Kamsa and promised to offer him every son which is born to him and Devaki. Agreeing to this, Kamsa sent them to their home. Devaki and Vasudeva went to their home. There, Devaki gave birth to her first child. The child was named Kirtimaan. They kept him at home. Now, as per the promise, Vasudeva, with a hard heart, took his first child in front of Kamsa and offered that child to Kamsa. Kamsa, on seeing Vasudeva’s sincerity, said, “This is your first child. I have a threat from your eighth child. So, keep him with you. I won’t kill him.” Now, Vasudeva was satisfied and came back to his home.
After Vasudeva went, Sage Narada came to Kamsa. Kamsa welcomed Sage Narada and performed Shodashopachara pooja to Sage Narada. Sage Narada, after the pooja, said to Kamsa, “You are sitting here ruling Mathura, and you don’t know this secret. All these Yadavas, Devaki, Vasudeva, and even your father Ugrasena, are all the incarnations of the devatas, who have incarnated to serve Lord Vishnu, in killing you. You are the demon Kaalanemi’s incarnation, who in your previous birth was killed by Lord Vishnu. That same Kaalanemi is born as you in this birth. All of these have incarnated to kill you. You think Devaki’s first child won’t harm you? You’re in such a delusion. The first son of Devaki can also be the eighth son of Devaki, and vice versa. So, you are on your own. Decide wisely, O King!” and Sage Narada went away.
On hearing this, Kamsa was very angry. He thought, “If I don’t imprison these people, then they might be a threat to me. I will imprison my father, Ugrasena, and rule Mathura. But what about Devaki and Vasudeva? If they remain in their house, that is also a problem for me, because Vasudeva is married to 13 wives, and Devaki is his 13th wife.”
Kamsa thought, “So, what if the eighth child is born to them, and for the sake of the child’s safety, they exchange it among his 13 wives and lie to me about the eighth child? No, no, this would not be right. I can’t let this eighth son of Devaki kill me. Therefore, I will imprison both Devaki and Vasudeva together, and separate his other 12 wives from him. By doing so, I can keep track of the children of Devaki and Vasudeva, and once the eighth son is born, I will kill him. In this way, I can be freed from my death, and the prophecy would be false, and I would rule everywhere.”
Thinking thus, Kamsa imprisoned King Ugrasena and became the king of Mathura. He imprisoned Devaki and Vasudeva and separated Vasudeva from his other 12 wives. Out of those wives, Rohini went and stayed in Nanda Gokula along with Nanda Maharaja and Yashoda. Vasudeva’s father, Shoorasena, had two wives. One was a Kshatriya Kanya, and another was a Vaishya Kanya. The son of Shoorasena's Kshatriya wife was Vasudeva, and the son of Shoorasena's Vaishya wife was Nanda Maharaja. This Nanda Maharaja was married to Yashoda.
So, Rohini, who was one of the wives of Vasudeva, lived with Nanda Maharaja and Yashoda Devi in Nanda Gokula. Now, Kamsa killed Devaki's first son. He killed the second, third, fourth, fifth, and sixth sons of Devaki. Why did this happen? There is a story behind this. From Lord Vishnu’s navel came Lord Brahma. Lord Brahma’s mind-born son was Sage Marichi. He had 6 sons. Once, these 6 sons teased Sage Devala. Enraged by this, Sage Devala cursed Sage Marichi’s 6 sons to be born as demons. Due to this curse, these 6 sons of Sage Marichi were born as the sons of Kaalanemi.
This Kaalanemi was the son of Hiranyaksha, the brother of Hiranyakashyapu. Hiranyakashyapu was ruling at that time. He had the power to bless and curse both. Hiranyakashyapu, in total ruled for even more than 6 crore years, as per the Mahabharata. So, these 6 sons were born of Kaalanemi. They went to do penance to please Brahma and to become powerful. Hiranyakashyapu got to know this. He thought, “When I have the capacity to bless and curse both, why did these morons go and worship Brahma?” And enraged by this, he cursed these 6 sons of Kaalanemi that, “May your own father kill you.” That Kaalanemi was born as Kamsa in this birth.
So, Hiranyakashyapu’s curse couldn’t be ignored because he had the power of penance; he did. Plus, these 6 children had to be killed by their own father. So, instead of being killed at birth, Lord Vishnu made them be born as the sons of Devaki and Kaalanemi, born as Kamsa. Because of this, Kamsa killed the 6 sons of Devaki. As Kamsa kept on killing these 6 sons, Yogamaaya Durgadevi, as per the instructions of Lord Vishnu, took the souls of each son and placed them in Paatalaloka. So, this was the reason why Sage Narada insisted that Kamsa kill the first child. Because he was eager for the appearance of Krishna. Plus, he too knew this story of the 6 children to be killed by Kamsa. So, that was also a part of this. So, there was no fault of Sage Narada by doing this.
After this, Devaki became pregnant for the seventh time. This time, Lord Vishnu instructed Aadishesha to enter Devaki’s womb. Carrying the instructions of His master, Aadishesha entered Vasudeva and then entered the womb of Devaki. Lord Vishnu sent Aadishesha first because, in the Ramavatara, this Aadishesha was Lakshmana and had served Lord Rama with great devotion. Because of that, Lakshmana had gained punya, which was beyond his competence or yogyata. Plus, Bhagavan is known as Edhamaanadvit in the Vedas, which means, ‘He reduces the excess punya of the people who gain punya beyond their own competence, and makes it equal to their yogyata or competence.’ Therefore, Bhagavan reduced that excess punya of Aadishesha by making him born before Bhagavan Himself.
Therefore, when in the future Krishna bowed to Balarama (Aadishesha), the excess punya would be reduced, and his punya would be equal to his yogyata, which is immense. Secondly, Bhagavan Vishnu is the supreme being; hence nobody can be His elder brother. That’s why He kept His Sankarshana form ( a form of Lord Vishnu) in Aadishesha and sent him into Devaki’s womb. Thus, Aadishesha had Sankarshana roopi Paramatma’s avesha within Him. Now, after 3 months of Devaki's pregnancy of Devaki, Lord Vishnu instructed Yogamaaya Durgadevi to transfer the seventh son of Devaki (who was Aadishesha) from Devaki’s womb to Rohini’s womb.
Rohini, too, had done penance to get a child who was very strong and was an incarnation of Aadishesha. That’s why Lord Vishnu asked Yogamaaya Durgadevi to transfer Aadishesha from Devaki’s womb to Rohini’s womb. But then, why was Aadishesha born in Devaki’s womb if he was to be transferred to Rohini’s womb? It was because Aadishesha was cleaning Devaki's womb of Devaki. After all, Lord Vishnu had to appear next. Therefore, Lord Vishnu’s stayplace should be clean, and Aadishesha is the servant of Lord Vishnu and is His bed. That’s why for 3 months in Devaki’s womb.
After this, when the seventh baby was transferred, the people started spreading the rumour that Devaki had a garbha paata (which means the baby died in Devaki’s womb). But they weren’t aware of the truth that happened. But then, after this, Lord Vishnu decided to appear on Earth to reduce the burden on Earth. The unborn Lord Vishnu entered Vasudeva, and after that entered Devaki’s womb, and stayed there for 7 months. Just as Lord Vishnu lives within everyone’s heart, in the same way Lord Vishnu stayed in Devaki’s womb. Just as if I get a fever, will Lord Vishnu, within my heart, get a fever? No. In the same way, Lord Vishnu was present in Devaki’s womb.
Plus, Devaki also doesn’t have the power to hold Lord Vishnu in her womb. Because Lord Vishnu holds the whole universe within His stomach (which is stated in the Vishnu Sahasranama as अन्तस्थं यस्य विश्वम्). Not only that, each of the strand of hair on His body has infinite universes within it. Within those universes, Lord Vishnu is present in every atom, and in all those Lord Vishnu’s hair strands there are again infinite universes. This goes on like that. Like this, He is Ananta koti Brahmanda Nayaka. Think about how heavy this Lord Vishnu might be. Can Devaki hold this heavy Lord Vishnu in her womb? No. Therefore, He is unborn.
But He is heavier than the heaviest things, and is lighter than the lightest thing in the universe. That’s why Bhagavan was just present in Devaki’s womb, not suffering at all as we do. Similarly, as per the instructions of Lord Vishnu, Lakshmidevi, who was Yogamaaya Durgadevi Herself, incarnated as the daughter of Yashoda and Nandagopa in Nanda Gokula. Yashoda hadn’t seen her daughter and had slept due to the tiredness from prasava. That’s why she is prayed as “गोपेन्द्रस्यानुजे ज्येष्ठे नन्दगोपकुलोद्भवे।” which means ‘the younger sister of Krishna (Gopendra), and who appeared in the lineage of NandaGopa.’
At the time of midnight, in Rohini Nakshatra, on Ashtami Tithi, when nature was happy, very auspicious omens were seen. The sages who did yagyas: the fire in the yagya kunda rose and was very bright. All the evil people were scared. All the noble people felt something which was making them utterly happy. At midnight, Lord Vishnu came out of Devaki’s womb and appeared in front of Devaki and Vasudeva. The Bhagavata describes Lord Vishnu, who came out of Devaki’s womb in His child form. The child was dark blue in color, like a rain-filled cloud. Lord Vishnu, in this child form, wore a crown decorated with different jewels, a kastoori tilaka on His forehead, and looked very attractive with lotus-like eyes; He was four-armed, holding a conch shell, discus, mace, and lotus. He had the Srivatsa sign on His chest, and was wearing the Kaustubha jewel in His neck. He had dazzling earrings that reflected the shine on His dark blue cheeks.
He was decorated with different ornaments and was wearing the Peetambara, which shone dazzlingly like lightning in the monsoon. The radiance from the child was so much that the whole jail, which was filled with darkness, was now filled with brilliant radiance, coming from the Lord in the form of a child. This radiance made the ornaments which He wore radiate even more brightly. This is when Lord Vishnu appeared on this earth to everyone as Krishna.
He instructed Devaki and Vasudeva to take Him to Nanda Gokula and bring the daughter of Yashoda here to Mathura. At the time of Krishna’s appearance, Kamsa and the soldiers who guarded the jail area all fell asleep due to the maya of Lord Vishnu. So, this story reveals the reason why Krishna was born as the 8th son of Devaki. This answer is very long, I know, but if you read till here, then thanks for reading. There was a sequence of events that, if not explained, would not lead to clarity as to why Krishna was the 8th son of Devaki. Woh kya haina…answer karte karte main khud katha me kho gaya…😁
WISHING EVERYBODY A HAPPY KRISHNA JANMAASHTAMI!!! 😊🙏✨🌸May Lord SriKrishna, who is the ocean of all auspicious qualities and is flawless, bless us with right knowledge, devotion in Him, and Gurus, health, wealth, abundance, a long, happy, prosperous, and meaningful life.
Hope this helps!
Jay SriRam!
ShriKrishnarpanamastu!