Śatapatha Brāhmaṇa ("of a hundred paths") 10.2.3.6

10.2.3.6

taddhaike uttarā vidhā vidhāsyanta etāṃśca prakramānetaṃ ca vyāmamanuvardhayanti yonimanuvardhayāma iti na tathā kuryānna vai jātaṃ garbhaṃ yoniranuvardhate yāvadvāva yonāvantargarbho bhavati tāvadeva yonirvardhata etāvatyu vā atra garbhasya vṛddhiḥ

Now, some, intending to construct higher forms (of altars), increase (the number of) these steps and this fathom accordingly, saying, 'We enlarge the womb in accordance therewith;'--but let him not do so; for the womb does not enlarge along with the child that has been born, but, indeed, only as long as the child is within the womb, does the womb enlarge, and so long, indeed, the growth of the (unborn) child here (lasts).