I believe in that time [1800s - 1970s] "good women" weren't to know about such things, like French Letters, or saying no, let alone use them. Husbands/men used them with "whores" not wives, and mostly only to prevent preg not disease; and this prevention to protect him not the outside woman, from future bastards looking for handouts from genetic dad.
Women were expected to be constantly preg, if that was God's Will and her husband's will, or lack of restraint. If she died she died. If he was an espec. doting husband, he might would introduce contra. for her life protection, but it wasn't expected or required of a husband; and considered somewhat suspect that he'd curtail his unlimited bare riding rights for a woman's protection, a woman who was fairly replaceable, like a horse. Unless, again, he was unusually found of the horse, uh, wife.
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Contraceptive collection comes to the Dittrick at Case
http://www.case.edu/artsci/dittrick/site2/news/contra.htm