...conclude that “shifting priorities” about family, careers, and how to allocate one’s time and resources is the most likely explanation for the dramatic reduction in rates of childbearing seen among more recent cohorts of young adults. We have not found compelling data support for more readily observed (and potentially altered) policy or economic factors, like the price of childcare or rent.
So, is this a problem to you at all? If it is, then how would you address it? If it isn't, is this a problem that can be addressed along with addressing what you believe is the greater problem? How?
It's not a problem anywhere because there are eight billion people on this planet. "Declining birth rates" is typically a thinly veiled racist talking point.