Śrīmad Bhāgavatam 10.55.2
sa eva jāto vaidarbhyāḿ
kṛṣṇa-vīrya-samudbhavaḥ
pradyumna iti vikhyātaḥ
sarvato 'navamaḥ pituḥ
"He took birth in the womb of Vaidarbhī from the seed (semen - Virya) of Lord Kṛṣṇa and received the name Pradyumna. In no respect was He inferior to His father."
