Health officials have had some success in battling the problem, but the figure is also poor in Sunderland where more than 20 per cent of mums-to-be are still using cigarettes.

Sunderland was one of the first areas in the country to provide a specialist stop smoking service for mums-to-be.

In just three years the team has cut the rates of smoking in pregnancy by more than seven per cent and has been hailed as a centre of excellence for best practice across England by the Health Commission.

However, latest figures still show 24.5 per cent in County Durham smoke throughout pregnancy, compared with 21.9 per cent of women on Wearside and a staggering 31 per cent in Hartlepool.

In the year 2002/2003, 29 per cent of all mums-to-be in Sunderland smoked throughout their pregnancies and the massive drop to 21.9 per cent is largely due to the success of the pregnancy stop-smoking service and the support it gives.

The team is co-ordinated by Sunderland Teaching Primary Care Trust and the consistent reduction in the number of smoking mums is well ahead of the Government targets of a 1 per cent reduction each year.

But, with still one in five women smoking while carrying their unborn child the team is determined to keep up the good work and help even more women give up smoking.

Gillian Murray, south of Tyne co-ordintor for the stop smoking in pregnancy service, said: "We work closely with many organisations, including GP surgeries, children centres, breastfeeding clinics, anyone who may come into contact with expectant and new mums to advise them of the help they can get.

"If women do want to quit we provide then and their families with the help and support they need. We do meet with the whole family because the mum will find it easier to quit if she has the backing of her family.

"What we don't do is lecture the mums or nag them because they get enough of people telling them smoking is bad, what they need is help and advice on ways to quit."

Gillian said also a huge part of the service is to work with mums who have just given birth to help them keep up the no-smoking.

Nationally between 50-70 per cent of new mums who have managed to quit during pregnancy relapse in the first three months of having their child.

She said: "People tend to use cigarettes to lean on when they are stressed and having to look after a new baby is a very stressful time, so we visit the mums every week to give them support."

* The special local Stop Smoking Helpline is 0800 587 4865 for any mum-to-be who wants to quit.