Having kids requires a physical act between a male and a female (assuming natural conception) and nothing more.
If all of your requirements were met before people had kids, there wouldn't be so many messed up people in this world. There probably wouldn't be nearly as many people, period...
I interpreted "roughly speaking" as wanting to skip over the obvious mechanical details like you mention and instead focus on the cultural norms affecting why Gen Z doesn't want children compared to previous generations.
bell-cot's comment is well aligned with https://www.thetimes.co.uk/article/young-put-off-having-chil... which is one of the cited sources. It starts "Only half of Generation Z and millennials plan to start a family as finances and global anxieties put them off having children, a survey found."
> If all of your requirements were met before people had kids
Again, "roughly."
Just like we know bell-cot's criteria aren't meant for a subsistence farming society, where the tradeoffs in having children are very different than in a high-technology culture, and just like we know it only make sense in a culture with access to effective birth control and family planning.
1. I'm terrified of childbirth and do not want to go through it.
2. Climate change -- I don't look forward to it myself and wouldn't want to bring more children to go through even worse conditions. I'll be adopting kids instead.
(1) A good, stable long-term relationship, with someone who seems to be good parent material
(2) A sense of long-term economic security, with a surplus sufficient to cover the costs of a kid
(3) A good, stable, kid-friendly housing situation
(4) Plenty of spare time, long-term (to be spent parenting)
What % of Gen Z feels that they have good prospects of achieving all 4 of those, before age 50?