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That form did not send anything, so no question about compression stockings or pregnancy and vein changes has reached a reader. Treat whatever you typed as unsent, because no copy of it exists here.
Back to the comparisons
Pick the comparison nearest your question. Compression options sit in the compression stockings guide. Questions about how pregnancy changes the veins, and when treatment can follow, sit under pregnancy and vein changes. Each page names the publisher behind every point and says where the evidence stops.
If you want outside reading first, a Cleveland Clinic page on spider veins and an NHS page on varicose veins are both reasonable starting points.