I have essentially been looking for a sex linked genetic defect which can be fatal, but most of them are exclusively male. This will have to be something that can turn up rather abruptly (in about 20-30 years) so that the entire population is not wiped out by time the story takes place. Parasites, atmospheric conditions, pretty much anything that might affect females but not males would be useful. A combination might even work.
I'm not sure if there is actually a way to do this, any help would be greatly appreciated. Something could be created, but I would prefer something with an actual basis.
Setting: roughly late 19th century/ early 20th century equivalent for the US. The technology includes x-rays, and basic (but crude) surgical procedures, but no designer drugs or understanding of genetics or disorders above the fact that they can be passed on from parent to child. Leaches are still in popular use for doctors.
googled/wikipedia: "sex linked defects" "female sex linked defects" female sterility" "gender gradients" "gender population" "gender distribution" "female infertility" "intersexuality" "females in population" Anything I missed feel free to tell me.
