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Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design.

ABSTRACT: Environmental tobacco smoke has an adverse association with preterm birth and birth weight. England introduced a new law to make virtually all enclosed public places and workplaces smoke free on July 1, 2007. We investigated the effect of smoke-free legislation on birth outcomes in England using Hospital Episode Statistics (HES) maternity data.We used regression discontinuity, a quasi-experimental study design, which can facilitate valid causal inference, to analyze short-term effects of smoke-free legislation on birth weight, low birth weight, gestational age, preterm birth, and small for gestational age.We analyzed 1,800,906 pregnancies resulting in singleton live-births in England between 1 January 2005 and 31 December 2009. In the 1 to 5 months following the introduction of the smoke-free legislation, for those entering their third trimester, the risk of low birth weight decreased by between 8% (95% confidence interval [CI]: 4%, 12%) and 14% (95% CI: 5%, 23%), very low birth weight between 28% (95% CI: 19%, 36%) and 32% (95% CI: 21%, 41%), preterm birth between 4% (95% CI: 1%, 8%) and 9% (95% CI: 2%, 16%), and small for gestational age between 5% (95% CI: 2%, 8%) and 9% (95% CI: 2%, 15%). The estimated impact of the smoke-free legislation varied by maternal age, deprivation, ethnicity, and region.The introduction of smoke-free legislation in England had an immediate estimated beneficial impact on birth outcomes overall, although we did not observe improvements across all age, ethnic, or deprivation groups.See video abstract at http://links.lww.com/EDE/B85.

SUBMITTER: Bakolis I

PROVIDER: S-EPMC5424880 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design.

Bakolis Ioannis I Kelly Ruth R Fecht Daniela D Best Nicky N Millett Christopher C Garwood Kevin K Elliott Paul P Hansell Anna L AL Hodgson Susan S

Epidemiology (Cambridge, Mass.) 20161101 6

<h4>Background</h4>Environmental tobacco smoke has an adverse association with preterm birth and birth weight. England introduced a new law to make virtually all enclosed public places and workplaces smoke free on July 1, 2007. We investigated the effect of smoke-free legislation on birth outcomes in England using Hospital Episode Statistics (HES) maternity data.<h4>Methods</h4>We used regression discontinuity, a quasi-experimental study design, which can facilitate valid causal inference, to an ...[more]

PMID: 27428672

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Project description:BackgroundThe relationship between exposure to conflict violence during pregnancy and the risks of miscarriage, stillbirth, and perinatal mortality has not been studied empirically using rigorous methods and appropriate data. We investigated the association between reduced exposure to conflict violence during pregnancy and the risks of adverse pregnancy outcomes in Colombia.Methods and findingsWe adopted a regression discontinuity (RD) design using the July 20, 2015 cease-fire declared during the Colombian peace process as an exogenous discontinuous change in exposure to conflict events during pregnancy, comparing women with conception dates before and after the cease-fire date. We constructed the cohorts of all pregnant women in Colombia for each day between January 1, 2013 and December 31, 2017 using birth and death certificates. A total of 3,254,696 women were followed until the end of pregnancy. We measured conflict exposure as the total number of conflict events that occurred in the municipality where a pregnant woman lived during her pregnancy. We first assessed whether the cease-fire did induce a discontinuous fall in conflict exposure for women with conception dates after the cease-fire to then estimate the association of this reduced exposure with the risks of miscarriage, stillbirth, and perinatal mortality. We found that the July 20, 2015 cease-fire was associated with a reduction of the average number of conflict events (from 2.64 to 2.40) to which women were exposed during pregnancy in their municipalities of residence (mean differences -0.24; 95% confidence interval [CI] -0.35 to -0.13; p < 0.001). This association was greater in municipalities where Fuerzas Armadas Revolucionarias de Colombia (FARC) had a greater presence historically. The reduction in average exposure to conflict violence was, in turn, associated with a decrease of 9.53 stillbirths per 1,000 pregnancies (95% CI -16.13 to -2.93; p = 0.005) for municipalities with total number of FARC-related violent events above the 90th percentile of the distribution of FARC-related conflict events and a decrease of 7.57 stillbirths per 1,000 pregnancies (95% CI -13.14 to -2.00; p = 0.01) for municipalities with total number of FARC-related violent events above the 75th percentile of FARC-related events. For perinatal mortality, we found associated reductions of 10.69 (95% CI -18.32 to -3.05; p = 0.01) and 6.86 (95% CI -13.24 to -0.48; p = 0.04) deaths per 1,000 pregnancies for the 2 types of municipalities, respectively. We found no association with miscarriages. Formal tests support the validity of the key RD assumptions in our data, while a battery of sensitivity analyses and falsification tests confirm the robustness of our empirical results. The main limitations of the study are the retrospective nature of the information sources and the potential for conflict exposure misclassification.ConclusionsOur study offers evidence that reduced exposure to conflict violence during pregnancy is associated with important (previously unmeasured) benefits in terms of reducing the risk of stillbirth and perinatal deaths. The findings are consistent with such beneficial associations manifesting themselves mainly through reduced violence exposure during the early stages of pregnancy. Beyond the relevance of this evidence for other countries beset by chronic armed conflicts, our results suggest that the fledgling Colombian peace process may be already contributing to better population health.

Project description:Smoke-free legislation has been a great success for tobacco control but its impact on smoking uptake remains under-explored. We investigated if trends in smoking uptake amongst adolescents differed before and after the introduction of smoke-free legislation in the United Kingdom.Prevalence estimates for regular smoking were obtained from representative school-based surveys for the four countries of the United Kingdom. Post-intervention status was represented using a dummy variable and to allow for a change in trend, the number of years since implementation was included. To estimate the association between smoke-free legislation and adolescent smoking, the percentage of regular smokers was modeled using linear regression adjusted for trends over time and country. All models were stratified by age (13 and 15 years) and sex.For 15-year-old girls, the implementation of smoke-free legislation in the United Kingdom was associated with a 4.3% reduction in the prevalence of regular smoking (P = .029). In addition, regular smoking fell by an additional 1.5% per annum post-legislation in this group (P = .005). Among 13-year-old girls, there was a reduction of 2.8% in regular smoking (P = .051), with no evidence of a change in trend post-legislation. Smaller and nonsignificant reductions in regular smoking were observed for 15- and 13-year-old boys (P = .175 and P = .113, respectively).Smoke-free legislation may help reduce smoking uptake amongst teenagers, with stronger evidence for an association seen in females. Further research that analyses longitudinal data across more countries is required.Previous research has established that smoke-free legislation has led to many improvements in population health, including reductions in heart attack, stroke, and asthma. However, the impacts of smoke-free legislation on the rates of smoking amongst children have been less investigated. Analysis of repeated cross-sectional surveys across the four countries of the United Kingdom shows smoke-free legislation may be associated with a reduction in regular smoking among school-aged children. If this association is causal, comprehensive smoke-free legislation could help prevent future generations from taking up smoking.

Project description:BackgroundOn 1 July 2007, smokefree legislation was implemented in England, which made virtually all enclosed public places and workplaces smokefree.ObjectivesWe examined trends in and predictors of secondhand smoke exposure among nonsmoking adults to determine whether exposure changed after the introduction of smokefree legislation and whether these changes varied by socioeconomic status (SES) and by household smoking status.MethodsWe analyzed salivary cotinine data from the Health Survey for England that were collected in 7 of 11 annual surveys undertaken between 1998 and 2008. We conducted multivariate regression analyses to examine secondhand smoke exposure as measured by the proportion of nonsmokers with undetectable levels of cotinine and by geometric mean cotinine.ResultsSecondhand smoke exposure was higher among those exposed at home and among lower-SES groups. Exposure declined markedly from 1998 to 2008 (the proportion of participants with undetectable cotinine was 2.9 times higher in the last 6 months of 2008 compared with the first 6 months of 1998 and geometric mean cotinine declined by 80%). We observed a significant fall in exposure after legislation was introduced--the odds of having undetectable cotinine were 1.5 times higher [95% confidence interval (CI): 1.3, 1.8] and geometric mean cotinine fell by 27% (95% CI: 17%, 36%) after adjusting for the prelegislative trend and potential confounders. Significant reductions were not, however, seen in those living in lower-social class households or homes where smoking occurs inside on most days.ConclusionsWe found that the impact of England's smokefree legislation on secondhand smoke exposure was above and beyond the underlying long-term decline in secondhand smoke exposure and demonstrates the positive effect of the legislation. Nevertheless, some population subgroups appear not to have benefitted significantly from the legislation. This finding suggests that these groups should receive more support to reduce their exposure.

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Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design.

Publications

Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design.

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