In the first of a series about motherhood and the role of the state in encouraging couples to have more children, the BBC News website's Clare Murphy asks why governments are so concerned about the size of their populations.

William The Conqueror was counting people nearly 1,000 years ago, and his European descendants are still at it. Small, today's politicians contend, isn't beautiful.

No EU country has the 2.1 birthrate needed to keep a population stable

Efforts to encourage couples to breed have a chequered history and, for many, recall fascist pasts. Mussolini heavily taxed single men in his Battle for Births, Hitler awarded medals to women with large families in his quest for a superior German race.

No-one is yet berating bachelors or mooting medallions for multiple births. But Europe's many governments are scrambling to find a solution.

Who cares?

Demographic decline causes anxiety because it is thought to go hand-in-hand with economic decline.

With fewer, younger workers to pay the health and pension bills of an elderly population, states face an unprecedented fiscal burden.

The dependency ratio of those aged 65 and over to those of working age looks set to double from one-to-four to one-to-two in 2050.

FERTILITY RATE In Europe 2.1 children per woman is considered to be the population replacement level. These are national averages Ireland: 1.99 France: 1.90 Norway: 1.81 Sweden 1.75 UK: 1.74 Netherlands: 1.73 Germany: 1.37 Italy: 1.33 Spain: 1.32 Greece: 1.29 Source: Eurostat - 2004 figures

At-a-glance: National policies

If current forecasts prove correct, then the US - which currently has 160m fewer people than the EU - will have equalled it by 2050.

Increasing immigration is, in theory, one option for Europe, but most agree it is politically unfeasible in the current climate.

Others stress that it would not in any event solve the problem in the longer term - the migrants would themselves grow old and their own fertility patterns would start to match those of the country which received them.

Another option is to increase the productivity of the working population, drawing more people into the workforce - and more controversially - making them stay there longer. But moves to raise the retirement age tend not to play well with electorates.

That leaves boosting birth rates.

Some analysts believe the fears are exaggerated. It seems richly ironic, they argue, to be worrying about falling numbers of people and, at the same time, to be fretting about the drain on natural resources, and the jostle for living space.

In addition, women's ability to control the number of children they have is a positive development, freeing them from a life of ongoing pregnancies.

Those who want to boost the birth rate do not necessarily disagree on this last point.

But, they wonder, are women restricting the size of families through free choice - or because financial concerns and worries about their position at work prevent them from having as many children as they might like.

Mixed messages

Many European countries already have policies in place - some more explicitly pro-natal than others.

Sweden, stressing gender equality rather than stating directly that it wants to boost birth rates, provides a mixed package of higher pay for women, flexible working for both parents and high quality childcare.

Who will support an ageing populace?

Other countries have also started toying with the idea of straight payments. Poland, where the population has fallen by half a million in the last six years, has recently passed legislation that will see women paid for each child they bear.

In Italy, where the population could shrink by as much as one third by 2050, one town has started offering couples 10,000 euros for each newborn baby.

How successful cash is as an incentive is still unclear. One study suggests that, even when cash allowances are boosted by 25%, the fertility rate climbs just marginally - perhaps by as little as 0.6%.

And the impact of generous maternity leave schemes and state-subsidised child care has also yet to be fully established.

Swedish and French birth rates may be higher than in much of Europe, but despite their respective systems, both countries still lag behind the holy grail of 2.1 children per woman needed to keep a population stable.

Europe is still feeling its way in this area, and may, some say, have to come to terms with the fact that there are women remaining childless or having small families by choice.

Recent evidence from Germany suggests that women may actually want fewer children than the two so often seen as the desirable norm - indeed some are happy with none at all.

Are falling birth rates something Europe should be worrying about? Or should countries embrace natural decline? What would persuade you to have more children? Send us your views using the link below.