The Compendium of Caraka 4.4.24

4.4.24

aṣṭame māsi garbhaśca mātṛto garbhataśca mātā rasahāriṇībhiḥ saṃvāhinībhirmuhurmuhurojaḥ parasparata ādadāte garbhasyāsaṃpūrṇatvāt / tasmāttadā garbhiṇī muhurmuhurmudā yuktā bhavati muhurmuhuśca mlānā, tathā garbhaḥ; tasmāttadā garbhasya janma vyāpattimadbhavatyojaso 'anavasthitatvāt/ taṃ caivārthamabhisamīkṣyāṣṭamaṃ māsamagaṇyamityācakṣate kuśalāḥ//

In the eighth month, the embryo and the mother repeatedly draw the ojas from each other—the embryo from the mother and the mother from the embryo—through the channels that carry chyle and circulate [fluids], because of the incompleteness of the embryo. Therefore, at that time the pregnant woman repeatedly experiences joy and repeatedly languishes, and likewise the embryo; therefore, at that time the birth of the embryo is accompanied by danger, because the ojas is unstable. And considering this very reason, the skilled declare the eighth month to be unaccountable.