Mahapadanasutta 1.19.1

1.19.1

Dhammatā esā, bhikkhave, yadā bodhisatto mātukucchiṃ okkanto hoti, na bodhisattamātu purisesu mānasaṃ uppajjati kāmaguṇūpasaṃhitaṃ, anatikkamanīyā ca bodhisattamātā hoti kenaci purisena rattacittena.

It’s normal that, when the being intent on awakening is conceived in his mother’s womb, she no longer thinks of men in a sexual way, and she cannot be violated by a man of lustful intent.