Benefits of smoking bans on preterm and early-term births: a natural experimental design in Switzerland

Comparison of statistical methods used to meta-analyse results from interrupted time series studies: an empirical study

BACKGROUND

The Interrupted Time Series (ITS) is a robust design for evaluating public health and policy interventions or exposures when randomisation may be infeasible. Several statistical methods are available for the analysis and meta-analysis of ITS studies. We sought to empirically compare available methods when applied to real-world ITS data.

METHODS

We sourced ITS data from published meta-analyses to create an online data repository. Each dataset was re-analysed using two ITS estimation methods. The level- and slope-change effect estimates (and standard errors) were calculated and combined using fixed-effect and four random-effects meta-analysis methods. We examined differences in meta-analytic level- and slope-change estimates, their 95% confidence intervals, p-values, and estimates of heterogeneity across the statistical methods.

RESULTS

Of 40 eligible meta-analyses, data from 17 meta-analyses including 282 ITS studies were obtained (predominantly investigating the effects of public health interruptions (88%)) and analysed. We found that on average, the meta-analytic effect estimates, their standard errors and between-study variances were not sensitive to meta-analysis method choice, irrespective of the ITS analysis method. However, across ITS analysis methods, for any given meta-analysis, there could be small to moderate differences in meta-analytic effect estimates, and important differences in the meta-analytic standard errors. Furthermore, the confidence interval widths and p-values for the meta-analytic effect estimates varied depending on the choice of confidence interval method and ITS analysis method.

CONCLUSIONS

Our empirical study showed that meta-analysis effect estimates, their standard errors, confidence interval widths and p-values can be affected by statistical method choice. These differences may importantly impact interpretations and conclusions of a meta-analysis and suggest that the statistical methods are not interchangeable in practice.

Evaluation of Population-Level Tobacco Control Interventions and Health Outcomes: A Systematic Review and Meta-Analysis

Importance

Smoking causes considerable noncommunicable diseases, perinatal morbidity, and mortality.

Objective

To investigate the associations of population-level tobacco-control policies with health outcomes.

Data Sources

PubMed, EMBASE, Web of Science, Cumulated Index to Nursing and Allied Health Literature, and EconLit were searched from inception to March 2021 (updated on 1 March 2022). References were manually searched.

Study Selection

Studies reporting on associations of population-level tobacco control policies with health-related outcomes were included. Data were analyzed from May to July 2022.

Data Extraction and Synthesis

Data were extracted by 1 investigator and cross-checked by a second investigator. Analyses were conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

Main Outcomes and Measures

The primary outcomes were respiratory system disease (RSD), cardiovascular disease (CVD), cancer, mortality, hospitalization, and health care utilization. The secondary outcomes were adverse birth outcomes, such as low birth weight and preterm birth. Random-effects meta-analysis was used to estimate pooled odds ratios (ORs) and 95% CIs.

Results

Of 4952 records identified, 144 population-level studies were included in the final analysis; 126 studies (87.5%) were of high or moderate quality. The most frequently reported policies were smoke-free legislation (126 studies), followed by tax or price increases (14 studies), multicomponent tobacco control programs (12 studies), and a minimum cigarette purchase age law (1 study). Smoke-free legislation was associated with decreased risk of all CVD events (OR, 0.90; 95% CI, 0.86-0.94), RSD events (OR, 0.83; 95% CI, 0.72-0.96), hospitalization due to CVD or RSD (OR, 0.91; 95% CI, 0.87-0.95), and adverse birth outcomes (OR, 0.94; 95% CI, 0.92-0.96). These associations persisted in all sensitivity and subgroup analyses, except for the country income category, for which a significant reduction was only observed in high-income countries. In meta-analysis, there was no clear association of tax or price increases with adverse health outcomes. However, for the narrative synthesis, all 8 studies reported statistically significant associations between tax increases and decreases in adverse health events.

Conclusions and Relevance

In this systematic review and meta-analysis, smoke-free legislation was associated with significant reductions in morbidity and mortality related to CVD, RSD, and perinatal outcomes. These findings support the need to accelerate the implementation of smoke-free laws to protect populations against smoking-related harm.

Smoking Ban Law in Chile: Impact in Newborns' Birth Weight by Women's Age Groups and by City Population Density

Objectives: We examined the short-term impact of the Smoking Ban Law (SBL) enacted in Chile in 2013 on low birth weight (LBW) rates in cities and its differential effects by different maternal age groups and city density. Methods: We included 885,880 live births from 21 Chilean cities of ≥100,000 inhabitants. We examined the smoking and LBW prevalence distribution before and after the SBL. Through Poisson mixed effect models, we determined whether a meaningful change in LBW rate occurred after SBL implementation in the whole sample and stratified by city population density and maternal age group. Results: LBW prevalence remained stable before and after the SBL implementation (6.1% and 6.3%, respectively), while women's smoking prevalence had a relative reduction of 25.9% (p < 0.00001). No significant changes in LBW rate occurred after the implementation of SBL in the total sample or stratified by city density tertiles or maternal age groups. Conclusion: SBL implementation did not show short-term impact on LBW rate in Chile. Further studies need to examine long-term impact of SBL on low birthweight.

Development of a Blueprint for Integrated Care for Vulnerable Pregnant Women

Purpose

There has been increasing awareness of perinatal health and organisation of maternal and child health care in the Netherlands as a result of poor perinatal outcomes. Vulnerable women have a higher risk of these poor perinatal outcomes and also have a higher chance of receiving less adequate care. Therefore, within a consortium, embracing 100 organisations among professionals, educators, researchers, and policymakers, a joint aim was defined to support maternal and child health care professionals and social care professionals in providing adequate, integrated care for vulnerable pregnant women.

Description

Within the consortium, vulnerability is defined as the presence of psychopathology, psychosocial problems, and/or substance use, combined with a lack of individual and/or social resources. Three studies focussing on population characteristics, organisation of care and knowledge, skills, and attitudes of professionals regarding vulnerable pregnant women, were carried out. Outcomes were discussed in three field consultations.

Assessment

The outcomes of the studies, followed by the field consultations, resulted in a blueprint that was subsequently adapted to local operational care pathways in seven obstetric collaborations (organisational structures that consist of obstetricians of a single hospital and collaborating midwifery practices) and their collaborative partners. We conducted 12 interviews to evaluate the adaptation of the blueprint to local operational care pathways and its’ embedding into the obstetric collaborations.

Conclusion

Practice-based research resulted in a blueprint tailored to the needs of maternal and child health care professionals and social care professionals and providing structure and uniformity to integrated care provision for vulnerable pregnant women.

Interrupted time series study found mixed effects of the impact of the Bavarian smoke-free legislation on pregnancy outcomes

In 2007 the German government passed smoke-free legislation, leaving the details of implementation to the individual federal states. In January 2008 Bavaria implemented one of the strictest laws in Germany. We investigated its impact on pregnancy outcomes and applied an interrupted time series (ITS) study design to assess any changes in preterm birth, small for gestational age (primary outcomes), and low birth weight, stillbirth and very preterm birth. We included 1,236,992 singleton births, comprising 83,691 preterm births and 112,143 small for gestational age newborns. For most outcomes we observed unclear effects. For very preterm births, we found an immediate drop of 10.4% (95%CI - 15.8, - 4.6%; p = 0.0006) and a gradual decrease of 0.5% (95%CI - 0.7, - 0.2%, p = 0.0010) after implementation of the legislation. The majority of subgroup and sensitivity analyses confirm these results. Although we found no statistically significant effect of the Bavarian smoke-free legislation on most pregnancy outcomes, a substantial decrease in very preterm births was observed. We cannot rule out that despite our rigorous methods and robustness checks, design-inherent limitations of the ITS study as well as country-specific factors, such as the ambivalent German policy context have influenced our estimation of the effects of the legislation.

Impact of expanding smoke-free policies beyond enclosed public places and workplaces on children's tobacco smoke exposure and respiratory health: protocol for a systematic review and meta-analysis

INTRODUCTION

Tobacco smoke exposure (TSE) has considerable adverse respiratory health impact among children. Smoke-free policies covering enclosed public places are known to reduce child TSE and benefit child health. An increasing number of jurisdictions are now expanding smoke-free policies to also cover outdoor areas and/or (semi)private spaces (indoor and/or outdoor). We aim to systematically review the evidence on the impact of these 'novel smoke-free policies' on children's TSE and respiratory health.

METHODS AND ANALYSIS

13 electronic databases will be searched by two independent reviewers for eligible studies. We will consult experts from the field and hand-search references and citations to identify additional published and unpublished studies. Study designs recommended by the Cochrane Effective Practice and Organisation of Care (EPOC) group are eligible, without restrictions on the observational period, publication date or language. Our primary outcomes are: self-reported or parental-reported TSE in places covered by the policy; unplanned hospital attendance for wheezing/asthma and unplanned hospital attendance for respiratory infections. We will assess risk of bias of individual studies following the EPOC or Risk Of Bias In Non-randomised Studies of Interventions tool, as appropriate. We will conduct separate random effects meta-analyses for smoke-free policies covering (1) indoor private places, (2) indoor semiprivate places, (3) outdoor (semi)private places and (4) outdoor public places. We will assess whether the policies were associated with changes in TSE in other locations (eg, displacement). Subgroup analyses will be conducted based on country income classification (ie, high, middle or low income) and by socioeconomic status. Sensitivity analyses will be undertaken via broadening our study design eligibility criteria (ie, including non-EPOC designs) or via excluding studies with a high risk of bias. This review will inform policymakers regarding the implementation of extended smoke-free policies to safeguard children's health.

ETHICS AND DISSEMINATION

Ethical approval is not required. Findings will be disseminated to academics and the general public.

PROSPERO REGISTRATION NUMBER

CRD42020190563.

Preterm birth and secondhand smoking during pregnancy: A case-control study from Vietnam

Background

The relationship between women who are exposed to secondhand smoke and preterm birth is still controversial. The present study aimed to examine the association between maternal secondhand smoking (SHS) during pregnancy and preterm birth.

Methods

A 1:1 case-control study was conducted at delivery room of The Women’s and Children’s Hospital of An Giang, Vietnam. A total of 288 cases of preterm birth and 288 controls included in this study. A structured questionnaire in a face-to-face interview was used to assess SHS and potential confounders (maternal age, body mass index, occupation, education level, parity, antenatal care visits, history of preterm birth, prenatal bleeding and preeclampsia/eclampsia).

Results

SHS was reported more frequently by women who delivered preterm babies compared with women of term deliveries (67.4% vs. 51.0%; P <0.001). After controlling all potential confounders, multivariable logistic regression analysis showed a relationship between SHS during pregnancy and preterm delivery (adjusted Odds ratio: 1.92; 95% CI 1.31, 2.81)

Conclusions

Our findings suggest that exposure to household tobacco smoke during pregnancy is associated with preterm birth.

Impact of Qingdao's smoke-free legislation on hospitalizations and mortality from acute myocardial infarction and stroke: an interrupted time-series analysis

BACKGROUND AND AIMS

More than 20 cities in China have enacted local smoke-free laws that prohibit smoking in public places. Only two of these cities have examined the health impact of the law. Enacted in 2013, Qingdao's smoke free-law was stricter than most other municipal smoke-free laws because it did not allow designated smoking rooms. This study aimed to estimate the impact of Qingdao's smoke-free legislation on acute myocardial infarction (AMI) and stroke.

DESIGN, SETTING AND PARTICIPANTS

We used an interrupted time-series design adjusting for underlying secular trends, seasonal patterns and meteorological factors to estimate the impact of the smoke-free law on AMI and stroke events among permanent residents aged 35 years or older in Qingdao, China. The study period was from 1 January 2010 to 31 December 2015, with a post-ban follow-up of approximately 2.5 years.

MEASUREMENT

Outcome measures were weekly numbers of hospitalizations and deaths due to AMI/stroke.

FINDINGS

A total of 10 371 and 56 101 patients were hospitalized, with a principal discharge diagnosis of AMI and stroke, respectively; 32 196 AMI and 49 711 stroke deaths occurred during the study period. Following the smoke-free legislation, an incremental 20% [95% confidence interval (CI) = 14-26%] and 8% (95% CI = 3-13%) decrease per year was observed in AMI and stroke hospitalization rates, respectively. Neither the immediate nor gradual change in AMI nor stroke mortality rates associated with the law was statistically significant (P > 0.05). Post-hoc subgroup analyses indicated that statistically significant reductions in AMI hospitalizations were evident among both the 35-64 (18% per year, 95% CI = 12-27%) and 65-84 (20% per year, 95% CI = 12-27%) age groups. Statistically significant reductions in stroke hospitalization were only in the older subgroup (13% per year, 95% CI = 8-18%).

CONCLUSIONS

The 2013 smoke-free legislation in Qingdao, China was associated with reduction in hospitalization from acute myocardial infarction and stroke among permanent residents aged 35 years or older. There was no statistically significant reduction in mortality from acute myocardial infarctions or stroke.

The impact of anti-tobacco legislation on birth weight in Peru

Background

Tobacco exposure remains a significant issue for public health, especially for pregnant women. It increases the risk for premature labor, low birth weight and small for gestational age (SGA), among other effects. To reduce these risks, many countries have enacted public policies to curb tobacco exposure. Peru enacted anti-tobacco laws that forbid smoking in public places, require prevention text and images in products and publicity, along with restriction of sales to adults. We evaluated the effect of the implementation of this law on newborn outcomes: birth weight, prematurity and SGA.

Methods

This was a quasi-experimental study that utilized data from the Peruvian Live Birth Registry. Children born to mothers from urban areas were the intervention group, while children born to mothers from rural areas were considered the control group. Only singletons with information on birth weight and gestational age, born to mothers aged 12 to 49 years were included in the study. In addition, newborns with birth weights greater than + 4 standard deviations (SD) or less than - 4 SD from the gestational age-specific mean were excluded. To measure the effect of legislation on birth weight we performed a difference in differences analysis.

Results

A total of 2,029,975 births were included in the analysis. After adjusting for characteristics of the mother and the child, and contextual variables, the anti-tobacco law in Peru reduced the incidence of prematurity by 30 cases per 10,000 live births (95% CI: 19 to 42).

Conclusions

The reform had negligible effects on overall birth weights and on the incidence of SGA. This modest result suggests the need for a more aggressive fight against tobacco, prohibiting all types of advertising and promotion of tobacco products, among others measures.

Three decades of inequality in neonatal and early childhood mortality in singleton births in Scotland

Background

Socioeconomic inequality in child mortality highlights opportunities for policies to reduce child deaths.

Methods

We used singleton birth, death and maternity records from Scotland, 1981-2011, to examine mortality rate differences by age across deprivation quintiles over time. We measured the difference between the most and least deprived quintiles (Q5-Q1) and the slope index of inequality (SII) across all quintiles-measures of the absolute deprivation gap, providing an indication of the public health impact.

Results

Q5-Q1 remained relatively constant from 1990 onwards for early neonates, widened in the mid-2000s for late neonates, increased in the 1990 s then decreased in the 2000 s in the post-neonates and declined over time in early childhood. The trend over time in SII showed no significant change for early neonates (P = 0.440), significant decrease for post-neonates (P = 0.010) and early childhood (P = 0.043), and significant increase for late neonates (P = 0.011).

Conclusions

Over three decades, the absolute deprivation gap in mortality widened in late neonates but stabilized or declined at other ages. This may reflect improved survival beyond the early neonatal period of babies with conditions related to socioeconomic inequality such as prematurity. Monitoring birth cohort data could enhance understanding of this vulnerable group.

Continued smoking versus spontaneous quitting among pregnant women living in a high risk environment

OBJECTIVES

In Hungary, 37% of women living in poverty were smokers in 2012. There are no valid data of pregnant women's spontaneous smoking cessation.

METHODS

Our retrospective cohort study (2009-2012) targeted the most underdeveloped regions with an estimated 6-8.5% of Roma population. The sample (N = 12,552) represented 76% of the target population i.e. women in four counties in a year delivering live born babies. Chi-square probe and multivariable logistic regression model (p < 0.05) were used to assess relationship between socio-demographic characteristics and spontaneous cessation.

RESULTS

Prior to pregnancy, the overall smoking rate was 36.8%. That of women in deep poverty and Roma was 49.7% and 51.1%, respectively. 70.3% of smokers continued smoking during the pregnancy. Among them 80.6% lived in deep poverty. Spontaneous quitting rate was 23.0%. Factors correlated with continued smoking included being Roma (OR = 1.95), undereducated (OR = 2.66), living in homes lacking amenities (OR = 1.48), and having regularly smoking partner (OR = 2.07). Cessation was promoted by younger age (≤ 18 years) (OR = 0.18), being married (OR = 0.50), and the first pregnancy.

CONCLUSIONS

Tailored cessation programmes are needed for Roma, older, low-income, and multiparous women who are less likely to quit on their own. Engaging husbands/partners is essential to reduce smoking among pregnant women and second-hand smoke exposure.

International variations in the gestational age distribution of births: an ecological study in 34 high-income countries

Background

Few studies have investigated international variations in the gestational age (GA) distribution of births. While preterm births (22-36 weeks GA) and early term births (37-38 weeks) are at greater risk of adverse health outcomes compared to full term births (39-40 weeks), it is not known if countries with high preterm birth rates also have high early term birth rates. We examined rate associations between preterm and early term births and mean term GA by mode of delivery onset.

Methods

We used routine aggregate data on the GA distribution of singleton live births from up to 34 high-income countries/regions in 1996, 2000, 2004, 2008 and 2010 to study preterm and early term births overall and by spontaneous or indicated onset. Pearson correlation coefficients were adjusted for clustering in time trend analyses.

Results

Preterm and early term births ranged from 4.1% to 8.2% (median 5.5%) and 15.6% to 30.8% (median 22.2%) of live births in 2010, respectively. Countries with higher preterm birth rates in 2004-2010 had higher early term birth rates (r > 0.50, P < 0.01) and changes over time were strongly correlated overall (adjusted-r = 0.55, P < 0.01) and by mode of onset.

Conclusion

Positive associations between preterm and early term birth rates suggest that common risk factors could underpin shifts in the GA distribution. Targeting modifiable population risk factors for delivery before 39 weeks GA may provide a useful preterm birth prevention paradigm.

Epidemiology of late preterm and early term births - An international perspective

Late preterm (34-36 weeks of gestational age (GA)), and early term (37-38 weeks GA) birth rates among singleton live births vary from 3% to 6% and from 15% to 31%, respectively, across countries, although data from low- and middle-income countries are sparse. Countries with high preterm birth rates are more likely to have high early term birth rates; many risk factors are shared, including pregnancy complications (hypertension, diabetes), medical practices (provider-initiated delivery, assisted reproduction), maternal socio-demographic and lifestyle characteristics and environmental factors. Exceptions include nulliparity and inflammation which increase risks for preterm, but not early term birth. Birth before 39 weeks GA is associated with adverse child health outcomes across a wide range of settings. International rate variations suggest that reductions in early delivery are achievable; implementation of best practice guidelines for obstetrical interventions and public health policies targeting population risk factors could contribute to prevention of both late preterm and early term births.

Smoking ban and health at birth: Evidence from Hungary

In 2012, smoking restrictions were extended to hospitality venues in Hungary. Women working in bars and restaurants were primarily affected by the intervention. In this research, we analyze the effect of this smoking ban on the outcomes of their pregnancies. Using individual live birth, fetal loss, and infant mortality registry data, we examine the probability of live birth, indicators of health at birth, and the probability of death in the first year of life. We apply a difference-in-differences framework and show that the smoking ban has improved health at birth. We observed birth weight to increase by 56 g (95% CI: 4.2 to 106.8) and gestation length by 0.19 weeks (95% CI: 0.02 to 0.36). Due to the ban, the probability of being born with very low and low birth weight has decreased by 1.2 and 2.2 percentage points, respectively (95% CI: -0.2 to -2.2 and 0.06 to -4.4), and we see a 0.9 percentage points reduction in the chance of being born very preterm (95% CI: -0.03 to -1.9). We also observe a decrease in the probability of being born with a low Ponderal index (decrease of 4.1 percentage points, 95% CI: -0.7 to -7.5). Performing a series of robustness and placebo tests, we provide evidence that supports the causal interpretation of our results. We also show that the ban was more beneficial for newborns of parents with low educational attainment and at the bottom of the fetal health endowment distribution.

Correlation between tobacco control policies and preterm births and low birth weight in Europe

OBJECTIVE

To assess the correlation between tobacco control policies- particularly smoking bans in work and public places-and the prevalence of preterm births and low birth weight in the European countries.

METHODS

This is an ecological study and the unit of analysis set at the country level. Tobacco control data in Europe were obtained for the years 2010 and 2013 as measured by the Tobacco Control Scale (TCS), which reflects the level of implementation of tobacco control policies. Prevalence data for preterm births and low birth weight were obtained from two sources: the European Perinatal Health Report (EPHR), which provides data for 2010, and the Eurostat data, which includes the years 2013 and 2014. We analyzed the correlation between the TCS score and the prevalence of preterm birth and low birth weight in the European countries by means of Spearman (rsp) rank-correlation coefficients and their 95% confidence intervals (95%CI).

RESULTS

The 2010 TCS was negatively correlated with the prevalence of preterm births before week 37 (rsp = -0.51; 95% CI: -0.77, -0.15; p = 0.006) and week 32 (rsp = -0.42; 95%CI: -0.73, -0.01; p = 0.030) and with the prevalence of the low birth weight (< 2500g, (rsp = -0.42; 95% CI: -0.66, -0.09; p = 0.028) in European countries in 2010. We found a statistically significant inverse correlation between the level of restrictions on smoking in public places and the prevalence of low birth weight (< 2500g rsp: -0.54; 95%CI: -0.72, -0.10; p = 0.017).

CONCLUSION

The level of smoke-free legislation in European countries correlates with lower preterm birth prevalence rates at the ecological level. Given the important negative effects of premature births for the public health system, these data support greater implementation of smoke-free policies and tend to support the implementation of tobacco control policies, but more research is needed.

Family Physicians' Perceived Prevalence, Safety, and Screening for Cigarettes, Marijuana, and Electronic-Nicotine Delivery Systems (ENDS) Use during Pregnancy

OBJECTIVE

Assess perceptions of prevalence, safety, and screening practices for cigarettes and secondhand smoke exposure (SHSe), marijuana (and synthetic marijuana), electronic nicotine delivery systems (ENDS; eg, e-cigarettes), nicotine-replacement therapy (NRT), and smoking-cessation medications during pregnancy, among primary care physicians (PCPs) providing obstetric care.

METHODS

A web-based, cross-sectional survey was e-mailed to 3750 US physicians (belonging to organizations within the Council of Academic Family Medicine Educational Research Alliance). Several research groups' questions were included in the survey. Only physicians who reported providing "labor and delivery" obstetric care responded to questions related to the study objectives.

RESULTS

A total of 1248 physicians (of 3750) responded (33.3%) and 417 reported providing labor and delivery obstetric care. Obstetric providers (N = 417) reported cigarette (54%), marijuana (49%), and ENDS use (24%) by "Some (6% to 25%)" pregnant women, with 37% endorsing that "Very Few (1% to 5%)" pregnant women used ENDS. Providers most often selected that very few pregnant women used NRT (45%), cessation medications (ie, bupropion or varenicline; 37%), and synthetic marijuana (23%). Significant proportions chose "Do not Know" for synthetic marijuana (58%) and ENDS (27%). Over 90% of the sample perceived that use of or exposure to cigarettes (99%), synthetic marijuana (99%), SHS (97%), marijuana (92%), or ENDS (91%) were unsafe during pregnancy, with the exception of NRT (44%). Providers most consistently screened for cigarette (85%) and marijuana use (63%), followed by SHSe in the home (48%), and ENDS (33%) and synthetic marijuana use (28%). Fewer than a quarter (18%) screened consistently for all substances and SHSe. One third (32%) reported laboratory testing for marijuana and 3% reported laboratory testing for smoking status.

CONCLUSION

This sample of PCPs providing obstetric care within academic settings perceived cigarettes, marijuana, and ENDS use to be prevalent and unsafe during pregnancy. Opportunities for increased screening during pregnancy across these substances were apparent.

Exploring the association between heat and mortality in Switzerland between 1995 and 2013

Designing effective public health strategies to prevent adverse health effect of hot weather is crucial in the context of global warming. In Switzerland, the 2003 heat have caused an estimated 7% increase in all-cause mortality. As a consequence, the Swiss Federal Office of Public Health developed an information campaign to raise public awareness on heat threats. For a better understanding on how hot weather affects daily mortality in Switzerland, we assessed the effect of heat on daily mortality in eight Swiss cities and population subgroups from 1995 to 2013 using different temperature metrics (daily mean (Tmean), maximum (Tmax), minimum (Tmin) and maximum apparent temperature (Tappmax)), and aimed to evaluate variations of the heat effect after 2003 (1995-2002 versus 2004-2013). We applied conditional quasi-Poisson regression models with non-linear distributed lag functions to estimate temperature-mortality associations over all cities (1995-2013) and separately for two time periods (1995-2002, 2004-2013). Relative risks (RR) of daily mortality were estimated for increases in temperature from the median to the 98th percentile of the warm season temperature distribution. Over the whole time period, significant temperature-mortality relationships were found for all temperature indicators (RR (95% confidence interval): Tappmax: 1.12 (1.05; 1.18); Tmax: 1.15 (1.08-1.22); Tmean: 1.16 (1.09-1.23); Tmin 1.23 (1.15-1.32)). Mortality risks were higher at the beginning of the summer, especially for Tmin. In the more recent time period, we observed a non-significant reduction in the effect of high temperatures on mortality, with the age group > 74 years remaining the population at highest risk. High temperatures continue to be a considerable risk factor for human health in Switzerland after 2003. More effective public health measures targeting the elderly should be promoted with increased attention to the first heat events in summer and considering both high day-time and night-time temperatures.

Effect of tobacco control policies on perinatal and child health: a systematic review and meta-analysis

BACKGROUND

Tobacco smoking and smoke exposure during pregnancy and childhood cause considerable childhood morbidity and mortality. We did a systematic review and meta-analysis to investigate whether implementation of WHO's recommended tobacco control policies (MPOWER) was of benefit to perinatal and child health.

METHODS

We searched 19 electronic databases, hand-searched references and citations, and consulted experts to identify studies assessing the association between implementation of MPOWER policies and child health. We did not apply any language restrictions, and searched the full time period available for each database, up to June 22, 2017. Our primary outcomes of interest were perinatal mortality, preterm birth, hospital attendance for asthma exacerbations, and hospital attendance for respiratory tract infections. Where possible and appropriate, we combined data from different studies in random-effects meta-analyses. This study is registered with PROSPERO, number CRD42015023448.

FINDINGS

We identified 41 eligible studies (24 from North America, 16 from Europe, and one from China) that assessed combinations of the following MPOWER policies: smoke-free legislation (n=35), tobacco taxation (n=11), and smoking cessation services (n=3). Risk of bias was low in 23 studies, moderate in 16, and high in two. Implementation of smoke-free legislation was associated with reductions in rates of preterm birth (-3·77% [95% CI -6·37 to -1·16]; ten studies, 27 530 183 individuals), rates of hospital attendance for asthma exacerbations (-9·83% [-16·62 to -3·04]; five studies, 684 826 events), and rates of hospital attendance for all respiratory tract infections (-3·45% [-4·64 to -2·25]; two studies, 1 681 020 events) and for lower respiratory tract infections (-18·48% [-32·79 to -4·17]; three studies, 887 414 events). Associations appeared to be stronger when comprehensive smoke-free laws were implemented than when partial smoke-free laws were implemented. Among two studies assessing the association between smoke-free legislation and perinatal mortality, one showed significant reductions in stillbirth and neonatal mortality but did not report the overall effect on perinatal mortality, while the other showed no change in perinatal mortality. Meta-analysis of studies on other MPOWER policies was not possible; all four studies on increasing tobacco taxation and one of two on offering disadvantaged pregnant women help to quit smoking that reported on our primary outcomes had positive findings. Assessment of publication bias was only possible for studies assessing the association between smoke-free legislation and preterm birth, showing some degree of bias.

INTERPRETATION

Smoke-free legislation is associated with substantial benefits to child health. The majority of studies on other MPOWER policies also indicated a positive effect. These findings provide strong support for implementation of such policies comprehensively across the world.

FUNDING

Chief Scientist Office Scotland, Farr Institute, Netherlands Lung Foundation, Erasmus MC.

Applying Precision Public Health to Prevent Preterm Birth

Preterm birth (PTB) is one of the major health-care challenges of our time. Being born too early is associated with major risks to the child with potential for serious consequences in terms of life-long disability and health-care costs. Discovering how to prevent PTB needs to be one of our greatest priorities. Recent advances have provided hope that a percentage of cases known to be related to risk factors may be amenable to prevention; but the majority of cases remain of unknown cause, and there is little chance of prevention. Applying the principle of precision public health may offer opportunities previously unavailable. Presented in this article are ideas that may improve our abilities in the fields of studying the effects of migration and of populations in transition, public health programs, tobacco control, routine measurement of length of the cervix in mid-pregnancy by ultrasound imaging, prevention of non-medically indicated late PTB, identification of pregnant women for whom treatment of vaginal infection may be of benefit, and screening by genetics and other “omics.” Opening new research in these fields, and viewing these clinical problems through a prism of precision public health, may produce benefits that will affect the lives of large numbers of people.

Smoke-free legislation and child health

In this paper, we aim to present an overview of the scientific literature on the link between smoke-free legislation and early-life health outcomes. Exposure to second-hand smoke is responsible for an estimated 166 ,000 child deaths each year worldwide. To protect people from tobacco smoke, the World Health Organization recommends the implementation of comprehensive smoke-free legislation that prohibits smoking in all public indoor spaces, including workplaces, bars and restaurants. The implementation of such legislation has been found to reduce tobacco smoke exposure, encourage people to quit smoking and improve adult health outcomes. There is an increasing body of evidence that shows that children also experience health benefits after implementation of smoke-free legislation. In addition to protecting children from tobacco smoke in public, the link between smoke-free legislation and improved child health is likely to be mediated via a decline in smoking during pregnancy and reduced exposure in the home environment. Recent studies have found that the implementation of smoke-free legislation is associated with a substantial decrease in the number of perinatal deaths, preterm births and hospital attendance for respiratory tract infections and asthma in children, although such benefits are not found in each study. With over 80% of the world’s population currently unprotected by comprehensive smoke-free laws, protecting (unborn) children from the adverse impact of tobacco smoking and SHS exposure holds great potential to benefit public health and should therefore be a key priority for policymakers and health workers alike.