Basically, our economic reality and expectations have come into conflict with biology and human lifespan.
If you want a secured dignified life and basic prerequisites to starting a family, every year that takes a little longer. And these days, almost everyone wants that dignified middle class life before they start a family.
A degree, an advanced degree, a good enough job, sufficient housing, a little fun to boot. Not until 25, 28, 30, 33, 35.
But we're supposed to have children in our early 20s. That's when we're strong and energetic enough, with good backs, and grand parents fit and willing to pitch in.
When we finally feel ready in our mid 30s, we find that time has conspired against us. Our parents are far away and often ailing and demanding care and attention. We have less energy and more stress and dread the lost sleep. We have the wisdom and worldliness to know just how hard this is going to be. And once we've metabolised all those things, that's when we realize that conception is no longer a question of a great night out and a few drinks. How many kids will be born at the end of that gauntlet? We're finding out right now.