I'm curious if any modeling has been done around 1 vs. 2 working-parent households in developed countries, in relation to population growth. Would we really be

I'm curious if any modeling has been done around 1 vs. 2 working-parent households in developed countries, in relation to population growth. Would we really be having a problem with "natives" not having kids if a single parent could work full time for a (very) comfortable lifestyle as it was just 40 years ago? It seems to me there is at least a correlation around the time a 2 parent household more or less became a requirement for the middle class to simply survive and when it became such a burden to raise a child. Since everyone is now more or less competing with 2x dollars for the same amount of fixed cost "stuff" (housing, education, healthcare, etc.) prices for those things rose substantially faster than inflation. Then you add in the second or third highest cost a dual-income family has (child care) that didn't really exist 40 years ago.... It seems at least obvious on it's face that this was going to happen. We removed any and all slack from our family lives, and wonder why we can't seem to get ahead when we have multiple decades of income hyper-planned in advance. I also think car culture and suburbification of many western countries also heavily contributed - at the same time we were forcing parents to both work outside the home, we also decided it wasn't cool to live near extended family or within a close-knit multi-generational community. Thus making the need for child care even more acute. I'm not entirely sure the point I'm making really - just that it seems so obvious. This outcome was practically written in stone on the policies (fiscal, social, and energy) western governments put in place since WWII.