Rather, as we have said, the sifting and selection of all the Ten Sefirot of Zeir Anpin takes place during the Pregnancy, but what is revealed in that period is a different matter. For Netzach-Hod-Yesod are revealed during the Pregnancy, while the rest still remain to be revealed. (Summary: The sorting and purification of all the Ten Sefirot is carried out during the Pregnancy, even though the repair of Hod-Yesod-Malchut is deficient. Nevertheless, only Netzach-Hod-Yesod are revealed during Pregnancy – for the embryo is “like a folded tablet, with only his legs visible” – Niddah 30b, “three within three”.)
Friday Evening and the Flow of Divine Light
Kalach Pitchei Chokhmah 121:11