The most common one I imagine is finances. I think there's a lot of people who see some level of stability and financial padding on the horizon, far away but w

The most common one I imagine is finances. I think there's a lot of people who see some level of stability and financial padding on the horizon, far away but within reach given a few years. Because this group sees that glimmer, they chase it and hold off on having kids in hopes of reducing the chances of ending up in dire straits thanks to the expenses that come building a family. The argument against this is that impoverished areas have higher birth rates, and that's probably because they don't see the glimmer. These people are more likely to have resigned themselves to their fate of being poor and kids either don't change that equation or even add value (as they can serve as farmhands and such). If we rewind several decades to when long-term financial stability wasn't so difficult to achieve, the birth rate wasn't an issue. People achieved stability when young and started having kids. If we want to bring the birthrate back up, I think it's going to be necessary to make that possible again.