The figures came from the Health Education Authority (HEA) as Public Health Minister Tessa Jowell announced plans for a major campaign to reduce smoking in pregnancy.

James Westhead, BBC Health Correspondent: " There is evidence that smoking during pregnancy is bad for the unborn child"

The campaign will include the setting up of a phone line smokers can call for advice.

A newborn baby exposed to smoke is more likely to suffer cot death, respiratory problems such as asthma attacks, and infections like bronchitis.

Few partners quit

The HEA report found women said that when they were pregnant, less than a third of their partners changed their smoking habits.

Smoking during pregnancy can affect the unborn child

Those who did were much more likely to cut down or just smoke away from their partner, the survey found.

The survey also found that while 65% of pregnant smokers had been advised to give up by their partners, only 25% found the comments useful.

Midwife Jennifer Percival: "It's hard to give up if your partner smokes"

Clive Bates, director of Action on Smoking and Health, said there were all-round benefits in quitting during pregnancy, but that it took some effort to make a successful attempt.

"What these figures mean, basically, is that men are not pulling their weight," he said. "It's really important for women to give up, but it's difficult if the man is smoking about the place."

Advantages to quitting

There were three main advantages in parents giving up, he said.

Clive Bates said there was shocking ignorance of the dangers of passive smoking

"First, the foetus isn't exposed to tobacco toxins in the womb.

"Second, the baby won't be exposed to passive smoking and is therefore less susceptible to cot death and respiratory disease.

"And third, children born to non-smokers are less likely to become smokers themselves."

However, he attacked the lack of knowledge about the dangers of passive smoking.

Ignorance of dangers

A recent report by the Doctor Patient Partnership found that 23% of adults said they did not know that parental smoking could lead to childhood health problems.

Mr Bates pointed to research conducted by the Royal College of Physicians of London that said 17,000 under-fives were admitted to hospital in the UK each year with passive smoking-related disorders.

Other studies have shown that passive smoking doubles the risk of acute respiratory illness in children, and if both mother and father smoke during the pregnancy, the baby is eight times more likely to die of cot death than if neither parent smoke.

"Parents are still largely unaware of the damage their smoking does to their kids," he said.