Ashtangasamgraha 2.18_2

2.18_2

ajātasya sākṣādannapānānanupraveśādamalatvācca rasasya garbhasya sthūlamalāsambhavaḥ evaṃ jaṭharastho garbho janmakāle tu prasūtimārutayogāt parivṛtyāvākśirā niṣkrāmatyanu cāparā cyutā mātṛhṛdayāt |

For the unborn, because food and drink do not directly enter and because chyle is free from waste, gross wastes cannot arise; the fetus thus situated in the abdomen, however, at the time of birth, due to the action of the labor wind, turns, emerges head downwards, and following it, the placenta detached from the mother's heart.