Britain's falling birth rate is being fuelled by a generation who would rather have fun and live comfortably than have children

BBC News:

The poll of 1,006 adults for the Guardian also suggested potential parents were forced to delay family life by career pressures.

Half of the adults quizzed said they found it increasingly difficult to find someone to have a family with.

It comes as French research suggests men's fertility fades after 40.

IVF experts looked at conception rates in nearly 2,000 couples at fertility clinics across France.

They found a woman under 30 was 25% less likely to conceive if her partner was 40 or older than if he was of a similar age.

Writing in the journal Fertility and Sterility, they concluded that men's fertility declines after the age of 40, just as women's fertility does after 35.

The Guardian poll suggested that those quizzed were aware of women's declining fertility, but that they had to balance financial and work pressures against this.

However, most men (64%) and most women (51%) said it was more important for women to enjoy themselves than have children.

A majority also said they believed doing well at work and earning money can count for more than bringing up children.

And only around a third of women believe people put children ahead of their careers.

When asked why the birth rate in Britain was low, people pointed to the cost of living and difficulty of combining work and family life.

Among both men and women, two thirds say career pressures make it harder to bring up children.

While more than half said the cost of child rearing was a deterrent.

Some 48% of people also blamed other social pressures such as less couples staying together than in the past.

While 37% thought that many people now leave it too late and miss the chance to have children.

Fertility experts have repeatedly warned women not to wait until their fertility declines to have children.

But over the last 20 years pregnancies in women over 35 have risen markedly and the average age of mothers is continuing to rise.

Some experts claim infertility will double across Europe within the next decade.

A spokeswoman for the Family Planning Association said things had changed both for women and men, with more choices and opportunities open to both.

"There are more things you can do in life, such as going off travelling and going to university.

"But it's actually quite a responsible thing to do, to wait until you are financially secure before having a family so that you can provide for your children."

Allan Pacey, secretary of the British Fertility Society and senior lecturer in Andrology at the University of Sheffield, said life was all about having fun and fertility experts did not want to spoil that, but he added that it was impossible to escape biology.

He said: "The data is absolutely clear that once women get to 35 their chances of conceiving fall dramatically. IVF doesn't necessarily work.

"There is also mounting evidence that men should be worried as well as this French research shows that when men go over 40 they are about half as fertile as men aged about 25."

Men should plan on parenthood by 40, new research reveals