COUPLES who are struggling to conceive are facing a postcode lottery in fertility treatment which is harming their prospects of having a baby.

The first report to show how health boards are performing against a new target to cut delays for in vitro fertilisation (IVF) shows centres in Aberdeen, Dundee and Edinburgh are hitting the goal early.

At the country's biggest unit, in Glasgow, it is a different story. Of those who started IVF in the city this summer, 63 per cent had waited for longer than the target of 12 months.

Patients may already have spent two years trying to conceive naturally before they are referred for IVF and, as they approach their late 30s, their chances of success recede. Delays beginning treatment can have a significant impact on a couple's chances of starting a family.

Professor Richard Fleming, an expert in fertility treatment at Glasgow University and founder of the Glasgow Centre for Reproductive Medicine, said: "The worst way you can treat infertility of any nature is to build in a delay."

The only NHS IVF centre in Glasgow, the West of Scotland assisted conception unit at Glasgow Royal Infirmary (GRI), has experienced two turbulent years.

In November 2012 there was a slump in the number of women successfully conceiving through IVF - and health board NHS Greater Glasgow and Clyde (GGC) began referring them to the city's private Nuffield Hospital instead. It was thought air pollutants from building works on the floor above the GRI unit may have been to blame.

This summer inspectors from the Human Fertilisation and Embryology Authority raised a new concern about the length of time patients referred to the Glasgow service had to wait to see a counsellor.

Yesterday, the statistics arm of NHS Scotland published the first picture of how the country's four IVF centres are performing against the new target to start preparing patients for their first IVF cycle within a year of referral. In total 494 patients were screened at an IVF centre in the three months to September. Around 71 per cent of eligible patients were screened for IVF treatment within 365 days - against a target of 90 per cent to be met by March 31.

This summer, 99 per cent of patients in Aberdeen, 100 per cent of patients in Dundee and 98 per cent of patients in Edinburgh started treatment in time.

For the Glasgow service, however, the figure was 37 per cent. Furthermore, patients living within the GGC health board boundary - rather than those referred by neighbouring boards - appear to be the worst affected.

Just seven per cent of the 149 NHS GGC patients who began IVF between July and September had waited less than 12 months. In comparison, 95 per cent of people from the Highlands and 98 per cent of patients from Lothian started within the 365-day time frame. All other health boards met the target in 100 per cent of cases.

Professor Fleming said that, by the age of 37, the chance of a couple conceiving through IVF treatment reduced by around two per cent a year. By the age of 39, he said, the chance of pregnancy was 20 per cent and by 40 it was 16 per cent. He said too many patients faced the ordeal of treatment delays.

"It is a pretty rough ordeal altogether," he said. "The majority of diagnoses are what they call 'unexplained' [infertility]. Those patients do not qualify until they have been two years trying. You then have another year wait. So that's three years since you embarked on realising this dream of having a family."

In a statement, NHS GGC implied it did not have capacity to meet the Scottish Government's target until it had completed a refurbishment of the GRI unit. In the meantime, it said, patients had been offered the opportunity to be treated in Lothian or Tayside. This summer 37 patients travelled for IVF in this way and all but one were treated within 12 months.

The health board said: "A £3.5 million refurbishment of the unit was completed earlier this year which provides us with the additional capacity to achieve the Scottish Government health department waiting-time target of 12 months for IVF treatment by the end of March 2015.

"In agreement with Scottish Government an arrangement is in place between NHS boards that, as part of a national commitment to reduce IVF waiting times, where appropriate, any spare capacity to treat patients more quickly within NHS Scotland assisted conception facilities should be used."

A Scottish Government spokeswoman said: "To support our IVF target, the Scottish Government has invested £12m over the last three financial years, specifically to reduce waiting times.

"This funding has had a dramatic impact with three out of the four centres already treating patients within 12 months of referral."

By the end of September, she said, the waiting times for IVF in Glasgow were around 15 months.