The demographic transition theory is usually applied to the Third World. It holds that with increasing affluence, and education of women, population numbers drop as women become feminists, and go for affluence and materialism over traditional roles and religion, and strop having babies. It is basically true of the West as well, with below replacement levels of population in Whites everywhere. Not even a lock down in a so-called pandemic change anything, as feminism is stronger:
  https://www.adelaidenow.com.au/news/opinion/tory-shepherd-we-did-not-get-busy-in-the-lockdown-australias-fertility-rate-is-forecast-to-drop-to-158-next-year/news-story/42e40be8c9ab7808d9d705baa1aa2b96

“Once upon a time – before the Great Toilet Paper Panic Buy – people thought there might be something a little sexy about a pandemic lockdown. Maybe there’ll be a ’rona baby boom, they sniggered. It wasn’t an entirely daft thought. In disasters people often press on the horn. Look at South Australia’s famous statewide blackout in September 2016, which brought on a little baby bump in June 2017. Turns out being cooped up with our loved ones because of a raging virus is not up there with candlelit dinners after a catastrophic power failure. We did not, dear friends, get busy in the lockdown. Australia’s fertility rate is forecast to drop to 1.58 next year. The Federal Government’s projection that it would hit 1.9 was, well, premature. That’s 1.58 babies per woman, which is well below what they call “replacement rate” and far lower than the 3.55 births per woman in 1961. That fall, on top of the slowdown in immigration, means that population growth will slow to a crawl. (Migrants not only bring themselves, they bring a higher fertility rate because they tend to be in the right age bracket). To get to replacement rate, you’d have to have at least an extra 42 per cent of a baby per woman. Tricky. We don’t know for sure why baby making hasn’t been a priority during the pandemic. It could be the sense of impending doom, the paralysing fear of the future, or simply too much talk of airborne snot particles. Maybe it was because, as a range of studies found, women have ended up doing more domestic labour during the pandemic. Even if they don’t have kids. And I imagine that child caring and homeschooling and working from home all at the same time has a powerful contraceptive effect. So there’ll be no wave of ’rona babies. But the fact is Australia’s fertility rate was sliding anyway, and even that 1.9 estimate was overcooked. We’re not alone – fertility rates are falling around the world. A study of 195 countries published in The Lancet in 2018 found, while populations are increasing in South Asia and sub-Saharan Africa, the fertility rate everywhere else is decreasing. In rich countries like Australia, the more education and the more access to contraception a woman has, the fewer babies she is likely to have. Women are waiting longer to have children, which tends to mean they have fewer, or none at all.”

     The article has the usual bow to immigration, but once migrant women are here, they too eventually embrace materialism, and fertility declines. Materialism ultimately leads to demographic suicide, in the long term. But until then, it’s party time.