SB 10.1.57

kīrtimantaṁ prathamajaṁ
arpayām āsa kṛcchreṇa
 so ’nṛtād ativihvalaḥ
kīrtimantam — by the name Kīrtimān; prathama-jam — the first-born baby; kaṁsāya — unto Kaṁsa; ānakadundubhiḥ — Vasudeva; arpayām āsa — delivered; kṛcchreṇa — with great pain; saḥ — he (Vasudeva); anṛtāt — from the breaking of the promise, or from fear of being a liar; ati-vihvalaḥ — was very much disturbed, being afraid.
Vasudeva was very much disturbed by fear of becoming a liar by breaking his promise. Thus with great pain he delivered his first-born son, named Kīrtimān, into the hands of Kaṁsa.

In the Vedic system, as soon as a child is born, especially a male child, the father calls for learned brāhmaṇas, and according to the description of the child’s horoscope the child is immediately given a name. This ceremony is called nāma-karaṇa. There are ten different saṁskāras, or reformatory methods, adopted in the system of varṇāśrama-dharma, and the name-giving ceremony is one of them. Although Vasudeva’s first son was to be delivered into the hands of Kaṁsa, the nāma-karaṇa ceremony was performed, and thus the child was named Kīrtimān. Such names are given immediately after birth.