Srimad Bhagavatam Canto 10, Chapter 05, Text 01-02


SB 10.5.1-2

sri-suka uvaca
nandas tv atmaja utpanne
jatahlado maha-manah
ahuya vipran veda-jñan
snatah sucir alankrtah
vacayitva svastyayanam
jata-karmatmajasya vai
karayam asa vidhivat
pitr-devarcanam tatha
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Sukadeva Gosvami said: Nanda Maharaja was naturally very magnanimous, and when Lord Sri Krsna appeared as his son, he was overwhelmed by jubilation. Therefore, after bathing and purifying himself and dressing himself properly, he invited brahmanas who knew how to recite Vedic mantras. After having these qualified brahmanas recite auspicious Vedic hymns, he arranged to have the Vedic birth ceremony celebrated for his newborn child according to the rules and regulations, and he also arranged for worship of the demigods and forefathers.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Srila Visvanatha Cakravarti Thakura has discussed the significance of the words nandas tu. The word tu, he says, is not used to fulfill the sentence, because without tu the sentence is complete. Therefore the word tu is used for a different purpose. Although Krsna appeared as the son of Devaki, Devaki and Vasudeva did not enjoy the jata-karma, the festival of the birth ceremony. Instead, this ceremony was enjoyed by Nanda Maharaja, as stated here (nandas tv atmaja utpanne jatahlado maha-manah). When Nanda Maharaja met Vasudeva, Vasudeva could not disclose, “Your son Krsna is actually my son. You are His father in a different way, spiritually.” Because of fear of Kamsa, Vasudeva could not observe the festival for Krsna’s birth. Nanda Maharaja, however, took full advantage of this opportunity.
The jata-karma ceremony can take place when the umbilical cord, connecting the child and the placenta, is cut. However, since Krsna was brought by Vasudeva to the house of Nanda Maharaja, where was the chance for this to happen? In this regard, Visvanatha Cakravarti Thakura desires to prove with evidence from many sastras that Krsna actually took birth as the son of Yasoda before the birth of Yoga-maya, who is therefore described as the Lord’s younger sister. Even though there may be doubts about the cutting of the umbilical cord, and even though it is possible that this was not done, when the Supreme Personality of Godhead appears, such events are regarded as factual. Krsna appeared as Varahadeva from the nostril of Brahma, and therefore Brahma is described as the father of Varahadeva. Also significant are the words karayam asa vidhivat. Being overwhelmed with jubilation over the birth of his son, Nanda Maharaja did not see whether the cord was cut or not. Thus he performed the ceremony very gorgeously. According to the opinion of some authorities, Krsna was actually born as the son of Yasoda. In any case, without regard for material understandings, we can accept that Nanda Maharaja’s celebration for the ceremony of Krsna’s birth was proper. This ceremony is therefore well known everywhere as Nandotsava.
Srimad Bhagavatam Canto 10, Chapter 05, Text 03