Bhagavatapurana 3.31.8

3.31.8

ulbena saṃvṛtas tasminn antraiś ca bahir āvṛtaḥ /
āste kṛtvā śiraḥ kukṣau bhugna-pṛṣṭha-śirodharaḥ //

7—8. Touched by the bitter, pungent, hot, salt, astringent sour and such other substances of painful effect, which are devoured by the mother and consequently suffering from pain produced all over the body; bound in a membraneous sheath (amnion) and surrounded on the outside with entrails it lies in that cavity with its head bent towards the stomach and with its back and neck bent (like a bow).