A few SF writers did have demographic collapse in their fiction, though usually for outside reasons, rather than the ones we're really seeing -- Philip K. Dick in The Gameplayers of Titan, for example, where there's been a precipitous drop in human fertility.
John Wyndham, The Chrysalids -- okay, it's a post-holocaust setting, but population is still dropping because of anti-mutant hysteria.
World Without Women, by Day Keene and Leonard Pruyn -- a plague wipes out virtually all women and sterilizes most of the survivors.
I'm sure there have been others. Possibly including Five to Twelve, by Edmund Cooper, but the world-building and genetics and other science in that are so vague and so screamingly nonsensical that it's hard to be sure.
I acknowledge, though, that they all required some outside agency, not just wealth and readily-available contraception.
no subject
John Wyndham, The Chrysalids -- okay, it's a post-holocaust setting, but population is still dropping because of anti-mutant hysteria.
World Without Women, by Day Keene and Leonard Pruyn -- a plague wipes out virtually all women and sterilizes most of the survivors.
I'm sure there have been others. Possibly including Five to Twelve, by Edmund Cooper, but the world-building and genetics and other science in that are so vague and so screamingly nonsensical that it's hard to be sure.
I acknowledge, though, that they all required some outside agency, not just wealth and readily-available contraception.