तस्मादाहुः सोष्यत्यसोष्टेति पुनरुत्पादनमेवास्य तन्मरणमेवावभृथः ॥ ३.१७.५ ॥
In plain words
Therefore they say, "She will bring forth," and "She has brought forth" — that is his second birth. And death is the final bath.
The commentators
Chāndogyopaniṣadbhāṣyam· bhāṣya
यस्माच्च यज्ञ पुरुष, तस्मात् त जनयिष्यति माता यदा, तदा आहुरन्ये सोष्यतीति तस्य मातरम्, यदा च प्रसूता भवति, तदा असोष्ट पूर्णिंकेति, विधियज्ञ इव सोष्यति सोम देवदत्त, असोष्ट सोम यज्ञदत्त इति, अत शब्दसामान्याद्वा पुरुषो यज्ञ । पुनरुत्पादनमेवास्य तत् पुरुषाख्यस्य यज्ञस्य, यत्सोष्यत्यसोष्टेति शब्दसम्बन्धित्व विधियज्ञस्येव । किंच तन्मरणमेव अस्य पुरुषयज्ञस्य अवभृथ, समाप्तिसामान्यात् ॥
In plain words
And because a human being is a sacrifice, when a mother is about to give birth to him, people say of her, 'She will give birth,' and when she has delivered, 'She has brought forth, O Purnika'—just as in a ritual sacrifice one says, 'Devadatta will press the Soma,' or 'Yajnadatta has pressed the Soma.' Therefore, by this similarity of terminology, man is indeed a sacrifice. The regeneration of this sacrifice called man—expressed in the words 'She will give birth' and 'She has generated'—is connected through words just like a ritual sacrifice. Furthermore, his death is the concluding bath of this human sacrifice, because both share the quality of bringing things to a close.
Close to the Sanskrit
And because man is a sacrifice, therefore when the mother will bring him forth, then others say regarding his mother 'she will give birth,' and when she has been delivered, then 'she has generated, O Purnika'; just like in the ritual sacrifice 'Devadatta will press Soma,' 'Yajnadatta has pressed Soma,' hence or due to similarity of words, man is a sacrifice. The regeneration indeed of this sacrifice named man, which is 'she will give birth,' 'she has generated,' is because of the word-connection like the ritual sacrifice. Moreover, that death of this human sacrifice is indeed the concluding bath, because of the similarity of completion.