The Compendium of Bheḷa 4.8.7

4.8.7

evaṃ hy asyāḥpratimāsaṃ[pratisaṃvartamānāyā yacchatanmataṃ] vartamānāyāḥ kukṣīkaṭīpārśvapṛṣṭhaṃ mṛdūbhavati jīrṇapurīṣaṃ cādhaḥ travetsukhaṃ ca prajāyate ||

For in this way, as she proceeds month by month, her belly, pelvis, flanks, and back become soft, digested feces flow downward, and she gives birth easily.