So you discount the idea that when people have the choice not to have large numbers of children (good healthcare to provide for old age, easily accessible contraception) they prefer to have fewer children?

Also, the central premise of the article seems to be in dispute:

Professor David Coleman from the University of Oxford said: 'Much has been written about the 'Death of the West', with its threatened demise reportedly due to the low level of reproduction in Western countries. We show that this so-called decline has been exaggerated and trends in European fertility have been misunderstood.

https://www.sciencedaily.com/releases/2015/04/150427211644.h...