Digging deeper 
'Problem: our existence is endangering the continued survival of the planet. Solution: we must not just limit the number of children being born, but we must actively support the extinction of the human race.
Sounds a little extreme perhaps, but climate change activists are increasingly calling for curbs on population growth, encouraging people not to have children in order to help save the planet. And some really do support the extinction of the human race.
Counterpointed against this, however, we have the equally compelling problem posed by the catastrophic drop in replacement fertility levels, where it's now recognised that women are no longer having sufficient numbers of children to sustain populations at a healthy level.
Climate change activists may think this is something to be celebrated, but the reality is that countries facing such a massive and irreversible decline in their population will increasingly become subject to societal disintegration, escalating violence, and financial collapse - which in turn heightens the possibility of war.
christiantoday.com and.god.said.whatever.you.do.dont.populate.the.earth
The factors around this are complex - why is fertility declining - is it culture or biology?
A rate of 2.1 children is considered to be replacement, but this was last seen in the EU around 1980. The average birthrate in 2020 was 1.5.
Biology
The overall natural fertility in men and women is falling at about 1% a year - ie 20% over 20 years - which is incredible. There are lifestyle factors like obesity - which can be resolved - but also what is thought to be the effect of Hormones of chemicals in plastics and other products that disrupt the ability to conceive the baby and carry the baby to term.
Some estimates put the world population at a turning point with numbers expected to fall.
Journalist Louise Perry spoke about The Case for Having Kids 'today only 3% of the world's population lives in a country whose fertility rate is not declining'.
Culture
Men and women are getting married later and having babies later in life (the average age of mother at first child is 31), which means less children.
The overall number of families is decreasing due to changes in attitudes to long-term relationships. The way we assess each other as future Mothers or Fathers, particularly from the woman's perspective, seems to be hardening. Women set the bar higher (56% in the US say they cannot find the partner they want vs 35% for men).
Men may feel the exercise of masculine traits (eg strength, protection) is not permitted, ironically making them less attractive as fathers and discouraging a sense of commitment and responsibility. See Fe/Maleness for more.
Where women do accept men, there may be a high rate of father abandonment, leaving one-parent families (3 million in the UK in 2021) and little opportunity for extending that family. These bad experiences are absorbed by children and siblings deterring their belief in possible stable relationships.
The increase of sex outside marriage may contribute to the lack of drive towards the commitment needed for having children. In the US in 2019 only 25% disapprove (ref) of sex in an unmarried ongoing relationship and about the same disapprove of casual sex. In the UK and Europe, in a different 2013 survey, the disapproval figure is around 15%. In the rest of the world it is considerably greater.
In the 70s and 80s reports like 'Limits to Growth' seemed to be predicting we'd be running out of oil by 1990, and created an atmosphere of constraint in the Boomer generation. There are now new felt constraints from Climate & Environment activism (eg of the D Attenborough type). Peter Meadows, one of the 'Limits to Growth' authors, has said chillingly that we need to reduce the world population from 7 billion to 1 billion, and he hopes that this extinction will be peaceful...
There have also been changes in tax law making families less supported (though apparently there is an intention to reverse this). Hungary has introduced new pro-family tax and other measures to help with children - and has seen an increase in the birth rate.
Be fruitful
So there are a lot of factors around this but we need to understand that God's mandate is to 'be fruitful and multiply'
We also need to see this reflected in our approaches to dating, approaching it with personal realism, and with hope and expectancy when we put God at the centre of our relationships. We should rejoice in children as Jesus does.
The family is the simplest and smallest unit of society and the real fountain of culture. If this fountain remains pure, man's culture has promise. But if it becomes polluted, all the rest will turn to dust and ashes, since the home is the foundation of the entire social structure.”
― Henry R. Van Til, The Calvinistic Concept of Culture
