There is one very key issue here that is often overlooked. Here are two datums. The first [1] is Chicago community areas by per capita income. The second [2] is the same areas by fertility rate. There is an extremely strong correlation between these two datums. This holds everywhere from our world at large, to individual countries, to even community areas within an arbitrary city in the US. The areas with the lowest fertility rate is "Loop" with a fertility rate of 24.3 and a per capita income of $65,526. The area with the highest fertility rate is South Lawndale with a fertility rate of 99.6, more than 400% that of Loop. And they have a per capita income of $10,402.

While there may be some exceptions, they are indeed the exception. This holds true everywhere. These [3] are data for the US as a whole contrasting fertility vs income. Once again those earning less than $10,000 have a fertility rate more than 20 points higher (150%) the rate of those earning $200k+ per year. And there is a disconcertingly smooth gradient in between. As an aside there are also strong links between fertility and low education and high religiosity as well as low income.

Think about what this means for each generation of children. An ever larger portion of children end up coming from these families with low income, low education, and high religiosity. And now this even larger portion of society will go on to spread their genes in a comparable way meaning you'll see an even higher chunk of children from the next generation coming from these groups. Poverty gets turned into a virus. Bringing people out of poverty might be a solution if not for the fact that then when people emerge from poverty, they stop having as many children.

And another issue here is that fertility rate understates the issue! When one group has the same number of children but has them younger, this has a direct effect on 'real' fertility rates. Imagine there are two groups with an identical fertility rate. However, one has children at 15 years of age on average, and another on 30 (using these numbers only for convenient math). By the time the 30 group has had their child the 15 group has had a child, and that child is now also having a child! You have the exact same fertility rate on paper, but in terms of population impact the young group has a 100% greater fertility rate.

Ultimately people who can in no way expect to be able to provide even a half decent upbringing for children need to stop having so many children. At the same time people who actually can afford to help provide a great life for a new generation need to stop being so self centered and do just that. Until that happens what do people expect to see? You're going to see poverty spreading rapidly even if it was holding completely level simply because you'll see more new people in poor families.

Keep in mind the twisted nature of exponential growth. If you have a population of 10,000,000,000 with a fertility rate of 2 and then a population of 10 with a fertility rate of 4, that population of 10 will become the majority and in the longrun approach becoming 100% of the population. You cannot overstate the relevance of fertility rates if you at all care about socioeconomic issues.

[1] - https://data.cityofchicago.org/Health-Human-Services/Census-...

[2] - https://data.cityofchicago.org/Health-Human-Services/Public-...

[3] - https://www.statista.com/statistics/241530/birth-rate-by-fam...