With fewer and fewer working-age people to support those who are retired, taxes will have to rise significantly.
But falling birth rates are not just a problem for the future.
Lloyd Cummins, from the Brighton and Hove City Mission, told GB News that three primary schools in deprived areas of Brighton have already been forced to close due to a shortage of pupils.
Falling birth rates can certainly be blamed on economic factors, and the consequences of the baby bust will be economic too.
Yet perhaps there are wider, more philosophical influences at play.
Tim Jones, of Brighton and Hove Faith in Action, told us that he believes a decline in the value that society places on children has been a major cause of falling family formation, as has the weakening of the social and community bonds that used to play a crucial role in sharing the burden of raising children beyond the nuclear family.
Demographic decline is one of the most difficult challenges facing Western nations.
Apart from Israel, all developed countries now have below-replacement birth rates, meaning that populations across the world are ageing steadily.
In extreme cases, like in South Korea, for example, the population is expected to shrink by an astonishing 75 per cent by the end of the century.
Different countries are experimenting with different solutions to the baby bust, including tax incentives, housing subsidies and benefits for young parents.
Whatever the answers to the crisis, the first step is to acknowledge its existence, something that we are barely beginning to do here in the UK.
But one thing is for sure: if treasured British cities like Brighton are to have any future at all, we must take the baby bust seriously.