Our generation did call them sanitary towels, although I remember an elderly aunt referring to sanitary napkins.
I would have told the uppish granddaughter that calling them sanitary towels was done because the makers of them regarded them as more sanitary than the home-knitted cotton towels that had to be washed, not because they or we found periods insanitary, just quite literally a bloody nusiance.
Yes, washable sanitary towels are better for the environment, even although they have to be both steeped, rinsed and washed at a hot temperature IF you make them yourself with no plastic, but the modern knitting patterns I have seen, tell girls to include a strip of plastic! Which is not good for the environment nor for the wearer!
A lot of European languages call them monthly cloths - which might offend the generation actually using them less than sanitary towels.