Fertility treatment on the NHS for every couple who needs it would quickly pay for itself in terms of long-term benefits to the economy and society, a study has found.

A child born by IVF will begin to repay all the public costs incurred by its upbringing - including the additional cost of the fertility treatment - just two years later than a child conceived naturally.

A separate study has found that making free fertility treatment available as part of a wider government policy could have a significant impact on stimulating the birth rate and combating the problems of an ageing population.

"Healthy people with infertility having children is not just of benefit to themselves and their families but also to society," said Professor William Ledger, head of the infertility unit at Sheffield University.

"If a government invests in IVF treatment ... [it] starts earning money back from tax and other benefits two years later than if that baby was conceived naturally," Professor Ledger said.

The study, released at the European Society of Human Reproduction in Prague, looked at how long it would take for a person conceived by IVF to pay off in taxes and national insurance contributions the £13,000 spent on average in test-tube conception. Professor Ledger said that, assuming full employment, a man conceived naturally would pay back about £160,000 net to the state compared with £147,000 net that would be paid back by a man born as a result of state-funded IVF.

The break-even point is 29 for a naturally conceived man and 31 for a man conceived through IVF.

The Government has promised to provide at least three cycles of fertility treatment on the NHS for every couple who need it, but current treatment is a postcode lottery, with some health trusts providing one cycle and others providing none.

Currently there are about 35,000 cycles of IVF treatment in Britain each year and about 10,000 live births, Professor Ledger said.

Jonathan Grant, a researcher with Rand Europe, an independent think-tank, has calculated that government-funded fertility treatment would stimulate the birth rate almost as much as some "child friendly" policies aimed at helping families, such as tax benefits.