It is sort of funny how any anti-natalist political position will get outbred out of existence haha. Reminds me of the Shakers who kind of died off because their belief system prevented procreation. https://en.wikipedia.org/wiki/Shakers
If that were true, birth rates wouldn't be declining in so many places. Any rational assessment would realize the correlation has nothing at all to do with genetics.
I wasn't blaming people's attitudes for the birth rate, just making observation about how any anti-natalist memes are likely fighting an uphill battle to propagate compared to memes that will get passed from parent to child
Similarly, there are religions that don't proselytize - like the fascinating Oahspe religion, which has about a dozen "Faithists" left, who meet on Skype.