A hundred years of incentives to multiply and multiply and multiply haven't had much effect in the OECD countries, whether you're talking a free fridge (yes, it's true) or higher taxes for not having babies. About the only thing that has worked--ever--is reducing the economic  disadvantage of childbearing to working women with generous parental leave lasting up to 1 - 2 years (combined mother and father--we have this in Canada), free or very affordable childcare, no professional penalties for work re-entry (Japan the worst offender), or the government basically relieving you of parenting (Norway) so that you can go back to work whenever you want to. No one wants to talk about these solutions but the fact is, once women gain access to employment, for the most part, they do not choose to have five, six, or seven children. However, with the right incentives, not the stupid ones, lots of them might be persuaded to have three, which is sufficient to support the aging sector.