The Population Division of the United Nations issued a report in 1999 on using migration to counteract the effects of low fertility on population size and ageing. The report looked at eight industrial countries and two regions, Europe and the European Union. Using population projections, the analysts estimated the amount of migration necessary to maintain both labour forces and the ratios of workers to retirees at a constant level.
This article agrees with the report that substituting migration for low fertility requires politically insupportable levels of migration. The article also concludes that the labour force and retirement financing outlook is not as dire as the UN report insinuates.