Public Release: 

Shopping vouchers could help 1 in 5 pregnant women quit smoking

University of Cambridge

Financial incentives could help one in five women quit smoking during pregnancy, according to new research published today in the journal Addiction. The study, led by researchers at the University of Cambridge and King's College London, found that only a small number of women 'gamed' the system to receive the incentives whilst continuing to smoke.

While the prevalence of smoking in pregnancy has declined, it remains high amongst more socially deprived groups. In England, one in eight (12%) of women smoke throughout pregnancy, ranging from one in 200 (0.5)%) in areas of low deprivation to one in four (27%) in areas of high deprivation. A recent review found that financial incentive schemes to be the single most effective intervention for encouraging women to stop smoking during pregnancy. However, this work was based on a few small trials in the USA and only measured smoking cessation after one week.

In order to assess the potential effectiveness of financial incentives and inform their use in clinical practice - and also to see to what extent it leads to mothers 'gaming' the system - researchers carried out a study of women attending antenatal clinics at a hospital in Chesterfield, Derbyshire, an area of high deprivation. 239 pregnant women - two out of five women who attended the clinic - enrolled into the financial incentives scheme.

At each visit to the antenatal clinic, the women were asked if they had smoked since the last visit and were given a carbon monoxide breath test (which showed positive if the individual had smoked in the preceding few hours). If they had not smoked, they were given a shopping voucher - the first voucher was worth £8 and the value increased by £1 for each visit up, providing a potential maximum of £752 in vouchers. Testing positive for smoking resulted in the incentive being withheld at that visit and the value being reset to £8 for the next visit; following two consecutive test results indicating no smoking, the incentive was re-set to the highest point attained prior to the lapse.

The researchers also used saliva samples from the women to assess at time of delivery and then six months later whether the women had stopped smoking, complemented with urinary and saliva tests at enrolment, 28 and 36 weeks into pregnancy and then two days and six months after the birth of their child.

Of the women who enrolled into the scheme, 143 received at least one voucher, suggesting that they had attempted to quit. One in five of the women (48 women) had managed to quit by the time of delivery. 25 women (4% of the entire cohort) were still not smoking six months after the birth of their child. This compared to the previous year, when only a very small number of women (less than 1%) were recorded as having stopped smoking. In all cases, women from areas of highest deprivation were the least likely to succeed in quitting. Urinary or salivary tests suggested that ten women (4%) had smoked cigarettes whilst claiming vouchers.

Professor Theresa Marteau from the Behaviour and Health Research Unit at the University of Cambridge, who led the study, said: "We all know of the dangers of smoking, particularly during pregnancy, but quitting can be extremely difficult. Offering financial incentives clearly works for some women - with very few 'gaming' the system and a significant number stopping smoking at least for the duration of their pregnancy."

Julie Hirst, Public Health Principal at Derbyshire County Council, said: "Giving every child the best start in life is crucial to promoting health and reducing health inequalities across the life course. Helping pregnant women to quit smoking is one of the most effective ways to achieve both of these outcomes. The health benefits for these babies and their mothers will be felt for the rest of their lives.

"Smoking is very addictive and these women have done incredibly well to quit. The incentive scheme gave them that bit of extra help that made all the difference. As a Council we are committed to extending this scheme the other areas of Derbyshire where there is a higher than average prevalence of smoking in pregnancy."

In total, £37,490 was spent on the financial incentive, which the researchers believe is likely to prove an acceptable ratio of cost to benefit. Based on modelling of other interventions for smoking cessation in pregnancy, they argue it is most likely that these schemes would fall within the acceptable range of cost effectiveness set by the National Institute for Health and Care Excellence (NICE).

Diana Ierfino from the Centre for the Study of Incentives in Health, King's College London, added: "The big question will be whether offering financial incentives is economically viable. Our estimates suggest that the ratio of cost to benefit is likely to be acceptable, given the financial implications of treating the health consequences of smoking.

"However, before a scheme like this is rolled out nationwide, there is still work to be done to understand the amount, frequency of type of incentives that would be most effective."

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The scheme was funded by NHS Derbyshire County Primary Care Trust and Derbyshire County Council, with funding for the evaluation coming from the Wellcome Trust.

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