Teenagers whose mothers smoked during pregnancy, or whose parents or friends smoke, are more likely to smoke themselves.
The findings come from a new study carried out at Imperial College London and published today in the journal Thorax, which highlights caregivers and friends as key drivers of children trying and taking up cigarette smoking.
The study, which looked at data on more than 11,500 children across the UK, shows that despite declining smoking rates in the UK since the 1970s, large numbers of early teens (aged approximately 14 years old) are still trying, or continuing, to smoke.
According to the researchers, the findings highlight the 'transmissible' nature of tobacco smoking - with teens far more likely to pick up the habit after exposure from friends and family - and support the need for measures to cut smoking rates among pregnant women as well as protecting children from smoking in the home.
Dr Anthony Laverty, from Imperial's School of Public Health and lead author of the research said: "Most smokers start in childhood and although smoking rates are coming down in both adults and children, large numbers of children in the UK still smoke. This represents a serious risk to their health throughout their lives as smoking kills one in every two smokers."
In the study, the team used data from the Millennium Cohort Study, which looks at children across the UK at regular intervals as they age. They analysed data on a total of 11,577 children to see which factors were linked to whether children had tried smoking or were current smokers.
Teens whose caregivers smoked were more than twice as likely to have ever smoked themselves. More than one quarter (26 per cent) of teens whose main caregiver smoked said they had tried cigarettes and five per cent said they were current smokers, compared with 11 per cent and one per cent among those whose caregivers did not smoke.
The analysis also revealed that approximately one in every three early teens (35 per cent) who reported that their friends smoked had tried cigarettes themselves, compared with just four per cent of those whose friends did not smoke. The risk of being a smoker was also shown to increase for children as the proportion of their friends who smoked increases.
In addition to the friends and family effect in teen years, the study revealed that being exposed to smoking in early life was associated with later smoking behavior - more than tripling their risk. Both children exposed to smoking in the same room when they were younger and those whose mothers smoked during pregnancy were more likely to be smokers.
The Millennium Cohort Study has been following a sample of children born in the UK in 2000/01 and involves interviews and questionnaire with the children and their caregivers on a range of factors. The results in this study are based on responses from 13- and 14-year-olds surveyed in 2014 and 2015. Overall, 1.9 per cent of children who took part were current smokers. Current smoking was more common in children from poorer families (14 times more likely in the poorest 20 per cent than the wealthiest 20 per cent) and in girls than boys (2.4 per cent versus 1.4 per cent).
"In order to protect children's health we need to do more to tackle smoking among parents, particularly when they are pregnant or their children are young, as well as encouraging smoking cessation and smoke-free homes," added Dr Laverty. "The link between children's smoking behaviour and that of their friends highlights how comprehensive interventions such as school-led strategies are needed. Smoking in pregnancy is also a risk, with around one in every 10 women still smoking while pregnant, so more needs to be done to support quitting, both for themselves and their children."
Dr Nicholas Hopkinson, senior author on the study from Imperial's National Heart and Lung Institute added: "Our findings highlight the 'transmissible' nature of the tobacco epidemic, both from parents to children and among friendship groups. Understanding and addressing this is going to be vital to achieve the government's Tobacco Control Plan target of a 'smoke-free generation'."
'Smoking uptake in UK children: analysis of the UK Millennium Cohort Study' by Anthony Laverty et al. is published in Thorax. DOI: 10. 1136/thoraxjnl- 2018- 212254