The Compendium of Caraka 4.8.39

4.8.39

sa yadā jānīyādvimucya hṛdayamudaramasyāstvāviśati, bastiśiro 'avagṛhṇāti, tvarayantyenāmāvyaḥ, parivartate+adho garbha iti; asyāmavasthāyāṃ paryaṅkamenāmāropya pravāhayitumupakrameta/

When one knows that the fetus, having left the cardiac region, enters her abdomen, engages the bladder neck, labor pains hurry her, and the fetus turns downward—in this state, having seated her upon a couch, one should begin to urge her to bear down.