Babies have always been expensive. The expense just happened to not be fully accounted for until recently.
Although, perhaps it could be better framed as the short term expense was not accounted for, whereas now, the long term expense is not accounted for.
Short term being less than a few decades and long term being more than a few decades.
There is also a collective vs individual expense aspect.
I also just feel like the basic calculus of this aspect for parents has changed as economies move up the value chain — I have relatives and childhood friends who grew up on farms, and they regularly helped out during busy times from a relatively young age (even if today they do all the schooling they are supposed to and don't go work full-time early one); meanwhile many people today will be in education with limited earnings until well into their twenties
This depends heavily on what time frame you're talking about.
For much of history people would often have children to work on farms and support the parents when they're older. Sometimes this support system was nuclear. Sometimes it was broader in society. So how do you account for "expensive" here? I honestly don't know.
But a lot of people focus on more modern times, particularly post-WW2, because the trend here is pretty much straight up. Education, housing and medical expenses have far exceeded inflation and real wages.
In more developed Asian countries (eg South Korea, Japan, China) the number of children has gone down in part because it is so expensive. In South Korea, so much is spent on tutoring to get into a good university to get a good job. The entire family's income is devoted to that. In China, for a man to be marriageable he often needs to pay the bride's family, have property, have a good job and so on. China has actually tried tackling some of this by popping the real estate bubble and outlawing private tutoring. Still, competition is intense and the bride price is still very real.
I think about the Fermi Paradox. What if the answer to why there are no galactic civilizations is as simple as "because capitalism"? Birth rates in developed countries are generally falling off a cliff as the barrier-to-entry gets increasingly higher.
> Babies have always been expensive.
They have always been expensive, and they have never been as expensive as today.
More than any other resource, babies require time. Talking purely from a US perspective, inflation adjusted income has never been higher.
https://fred.stlouisfed.org/series/mehoinusa672n
When we earn more, the time spent to care for a baby 'costs' more because it's time not spent working. It's time not spent continuing your education. It's time not spent doing some expensive bougie luxury like paying someone else to cook you a meal.
It's a similar reasoning as to why working hours have only dropped a bit. When we earn more per hour, we can afford the same quality of life with fewer hours worked. However it also means each hour we choose not work is costing us more in opportunity cost. So we choose to work more.
Still, considering how many years we spend in education with little to no employment, and how many years we are currently able to live after we have retired, the % of our lifetime spent working has never been lower.