This whole article is about someone with a huge and inexplicable woman problem, but this is the part where I can add some info myself.

This book is jaw-dropping as a record of misogyny and intriguing as a document of social history. Were safety pins truly so upsetting, because of their association with sanitary pads? Or did Horton lose his mind in the course of this sentence? (And was Mum an analgesic, perhaps for painful menstruation? The word doesn’t have great SEO, so I’m not sure; historians of medicine may know.)

Mum was the first commercially-marketed deodorant and is still sold today in many countries.

And yes, safety pins were often at that time only found in sanitary pad/napkin packaging, so inextricably linked to that in men’s minds.