Bhashya
अथ यदूर्ध्वं मध्यन्दिनात् प्रागपराह्णात् यद्रूपं सवितुः, स प्रतिहारः, तदस्य गर्भा अन्वायत्ताः ।अत ते सवितुः प्रतिहारभक्तिरूपेणोर्ध्वं प्रतिहृताः सन्तः नावपद्यन्ते नाधः पतन्ति, तद्द्वारे सत्यपीत्यर्थः ।यतः प्रतिहारभाजिनो हि एतस्य साम्नो गर्भाः ॥
In plain words
Now, that aspect of the sun which appears between midday and the afternoon is the pratihāra, and the embryos in the womb depend upon it. Therefore, being sustained upward by this solar pratihāra, they do not fall down, even though the passage for birth is open. This is because they partake of this Sāman.
Close to the Sanskrit
Now, what form of the sun is after midday and before afternoon, that is the pratihāra; to it the embryos are connected. Hence, being held upward by the sun's pratihāra-bhakti form, they do not fall down, even though that pathway is present, such is the meaning. Because the embryos are partakers of this Sāman.