[452] "Bhikkhus, it is upon the coming together of three things that the descent of the embryo (gabbhassāvakkanti) takes place. Here, the mother and father have come together, but the mother is not in season, and the gandhabba is not present — in that case there is as yet no descent of the embryo. Here, the mother and father have come together, and the mother is in season, but the gandhabba is not present — in that case there is as yet no descent of the embryo. But when, bhikkhus, the mother and father have come together, and the mother is in season, and the gandhabba is present — thus, upon the coming together of these three things, the descent of the embryo takes place.
Then, bhikkhus, the mother carries that embryo in her womb for nine or ten months, a heavy burden, with great anxiety. Then, bhikkhus, at the end of nine or ten months, the mother gives birth to that heavy burden with great anxiety; and when it is born, she nourishes it with her own blood."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.