When you save the SVG as PDF, is the whole drawing rasterized? Or does it only get rasterized after it is in Word? It should remain as vector (except for the patterns) after saving as PDF. But I don't know what effect it has when the PDF goes into Word.
Maybe the means of putting the PDF into Word matters? How do you do it? Is it imported? Or embedded? Or something else?
Would it work for you if only the pattern part is rasterized, while everything else remains vector? I wonder if, instead of patterns, if you select the pattern filled objects, and use Edit menu > Make a Bitmap Copy (makes the selection into PNG image) - would that work? I wonder if converting the pattern into PNG would allow them to be displayed, when saving the file as SVG?
It looks like the only way to have the hatch fill as vector, is to draw it as vector. I don't know why the pattern fill is not showing in Word. But maybe using Bitmap Copy in the SVG file, they would be displayed?