The thesis that liberal societies are not replacing themselves seems incorrect. UK population was 60 million in 2000, and is 67.5 million today. The demographics are somewhat interesting in that 'white native British' has dropped from 99% or so of the population in the 1950s to about 82% today. In comparison the USA population is also steadily rising from ~280 million in 2000 to ~330 million in 2020. Now if the concern is that the relative ratios of different race-ethnic-religious groups is changing, why is that an issue? Children tend to adopt the societal norms they're surrounded by, even if this upsets their traditional-minded parents. That's certainly been the case in the USA, it's an assimilative process.<p>As far as birth rate data, as women acquire more rights and wealth they tend to choose to have fewer children later in life, and as medical care and knowledge improves, those children tend to survive to adulthood at rates unheard of a few centuries ago. Thus, while birth rates may indeed be falling, the population is stable or even growing due to the other factor the author seems to ignore, i.e. lower childhood death rates.