High female employment also means high fertility says Kevin Daly

Kevin Daly, economist with investment bank Goldman Sachs, said it was a myth that in developed countries women either chose paid work or babies.

But Mr Daly told Radio 4's More Or Less that such countries had to reach a certain level of development.

"It is counter-intuitive to the traditional view of working and having children," said Mr Daly.

Mr Daly, a senior economist at Goldman Sachs, checked the numbers for family size, country by country, next to the levels of female participation in the labour market and found that in developed countries, the numbers went up together.

"Initially I was surprised at this data.

"It's also very refreshing then to find something like this, where there's important social implications but also intuitive financial market implications that follow from such an important social issue," he added.

Mr Daly said underdeveloped countries had a combination of low numbers of women in the workforce and high fertility rates

In some societies it is not easy to combine paid work and motherhood

"Essentially in these countries it is impossible for women to work at all," he added.

"When you then emerge from that into the second stage of development, where women can work but society is set up and laws and tax policies are set up, that it is very difficult for women to combine employment with child care.

In such scenarios, you find that both employment and fertility suffer. Within such a group are countries such as the Mediterranean countries and also Japan, where you have both very low fertility rates and also very low female employment."

Million influences

Mr Daly said there was a third level of countries in which society made it easier to combine paid employment and having children.

"In such a scenario, fertility rates and female employment both tend to be considerably higher," he said.

But he also said: "Economists need to be very careful in the treatment of the data and as a micro-economist, I wouldn't claim that this single factor explains all the variation in fertility rates across countries.

"There are a million other influences on the decisions that families make. I think what is interesting is the that the result will be counter intuitive to many."