Expectant mothers are being pressed to give up smoking to reduce the risk of seriously affecting the health of their babies.

Norfolk has the second highest number of women who smoke while pregnant in the East of England, and Norfolk City Council Public Health is launching a drive to raise awareness of risks.

Smoking while pregnant is harmful for both the mother and the unborn child. Carbon monoxide and other chemicals found in cigarettes enter the mother's blood and limit oxygen to the baby.

Research shows that there are a number of birth defects associated with smoking during pregnancy, including an increased risk of premature birth, being born too small, or even dying before birth.

The impact of being exposed to smoke may not be confined to infancy. It has also been linked to poorer growth and physical development after birth into adulthood.

Research shows that smoking in pregnancy is associated with increased risk of babies being born with congenital heart defects or developing problems in childhood such as asthma and attention deficit hyperactivity disorder (ADHD). Babies born to mothers who smoke also have three times the risk of sudden infant death syndrome (SIDS).

Margaret Dewsbury, Chairman of Norfolk County Council's Communities Committee, said: 'Although the rate of smoking during pregnancy has come down in Norfolk in recent years, it's still higher than we would like it to be.

'There are significant variations in the rates throughout the county. Norwich and Great Yarmouth have higher rates than the national average of 10.6pc so these are the areas that we will concentrate on most with the campaign.'

Quitting will improve the health of the mother and child immediately. The baby is less likely to be born premature and face the additional breathing, feeding and health complications that are linked with that.

The baby is also less likely to be born underweight. Infants of women who smoke are, on average, 200g (about 8oz) lighter than others, making them more prone to infection.

Dr Louise Smith, Director of Public Health for Norfolk, said: 'We are working closely with others in the county to tackle the levels of smoking during pregnancy.

'All midwives carry out carbon monoxide tests on pregnant women and if the levels indicate they have been exposed to smoke they are offered an appointment with the stop-smoking service.

'Some mothers-to-be are reluctant to seek help to stop smoking because they're worried that they may be harming their baby, but it's still worth stopping even if you've smoked at the start of your pregnancy.

'If you quit by the 15th week of your pregnancy, the risk of your baby being born too early or having a low birth weight is the same as that of a non-smoker.'

When one woman discovered she was pregnant, she wanted to protect her baby and went to Norfolk's stop smoking service for advice about how to give up.

Lisa said: 'I'd tried to quit smoking twice before but found that willpower alone just wasn't enough. Being pregnant gave me the extra incentive I needed. The stop smoking service gave me fantastic support.

'I didn't feel judged and they were really helpful, even offering appointments at times to suit me. I'm thrilled and proud to have finally quit and I'm very grateful for all the support I received as I couldn't have done it alone.'

Pregnancy and motherhood are great incentives to quit smoking. Pregnant women who are struggling to give it up can talk to their midwife or contact Norfolk's specialist stop smoking services.

Advisors there work with mothers to find what works best, offer support, group sessions, one-to-one appiontments, and drop-in sessions at the different locations around the county.