SB 6.14.30

sāpi tat-prāśanād eva
 citraketor adhārayat
garbhaṁ kṛtadyutir devī
 kṛttikāgner ivātmajam
Word for word: 
— she; api — even; tat-prāśanāt — by eating the remnants of food from the great sacrifice; eva — indeed; citraketoḥ — from King Citraketu; adhārayat — bore; garbham — pregnancy; kṛtadyutiḥ — Queen Kṛtadyuti; devī — the goddess; kṛttikā — Kṛttikā; agneḥ — from Agni; iva — as; ātma-jam — a son.
Translation: 
As Kṛttikādevī, after receiving the semen of Lord Śiva from Agni, conceived a child named Skanda [Kārttikeya], Kṛtadyuti, having received semen from Citraketu, became pregnant after eating remnants of food from the yajña performed by Aṅgirā.