OUP user menu

Increased health risks of children with single mothers: the impact of socio-economic and environmental factors

Marion Scharte, Gabriele Bolte,
DOI: http://dx.doi.org/10.1093/eurpub/cks062 469-475 First published online: 9 June 2012

Abstract

Background: Adverse effects of single parenthood on children’s health have been reported before. Socio-economic difficulties are discussed as mediating factors. As child health also depends on environmental conditions, we investigated the impact of environmental exposures and socio-economic factors on differences in health outcomes of children with single mothers vs. couple families. Methods: Data on 17 218 pre-school children (47% female) from three cross-sectional surveys conducted during 2004–07 in Germany were analysed. Health and exposure assessment were primarily based on parental report. Effects of socio-economic indicators (maternal education, household income) and environmental factors (traffic load at the place of residence, perceived environmental quality) on associations of four health outcomes (parent-reported health status, asthma, overweight, psychological problems) with single parenthood were determined by logistic regression analyses. Results: Children with single mothers showed an increased risk regarding parent-reported poor health status [boys: odds ratio (OR) 1.39 (95% confidence interval (CI): 1.06–1.82), girls: 1.73 (1.28–2.33)], psychological problems [boys: 1.90 (1.38–2.61), girls: 1.58 (1.03–2.42)], overweight [only boys: OR 1.23 (1.01–1.50) and asthma [only girls: OR 1.90 (1.15–3.15)]. Adjusting for socio-economic factors attenuated the strength of the association of family type with child health. Although environmental factors were associated with most health outcomes investigated and children of single mothers were more often exposed, these environmental factors did not alter the differences between children with single mothers and couple families. Conclusions: The increased health risks of children from single-mother families vs. couple families are partly explained by socio-economic factors, but not by the environmental exposures studied.

Introduction

The adverse effect of single parenthood on different aspects of child health has been previously shown by several studies, although the contribution of socio-economic factors is still a matter of debate. Two British studies found that material disadvantages could fully or largely explain adverse effects of single parenthood on psychological well-being1 and physical health.2 In a large Canadian longitudinal survey, the increased psychiatric and academic problems in children of single mothers were largely explained by household income.3 In contrast, adjusting for socio-economic status attenuated only moderately the increased risk of psychiatric diseases of children and of all-cause mortality in boys in single-parent families compared with those in two-parent families in a Swedish study.4

These conflicting results might be in part due to differences in study designs, study populations or health outcomes investigated. Furthermore, as these studies were performed in different countries, the differences in the social, political and economic context of the respective country might contribute to the discrepant findings. In Germany, the risk of relative poverty has increased profoundly during the last 15 years, especially among single-parent families. In 2008, 40% of the single-parent families had a household income below the poverty threshold.5 Against the background of increasing poverty rates especially among single-mother families in Germany, a rising proportion of children in single-parent families might have an increased risk to develop health problems.

Besides income and maternal education, the health of children is influenced by environmental conditions. Several studies support the impact of environmental factors such as built environment and traffic-related exposures on overweight and asthma, respectively.69 Furthermore, it has been previously shown that a low socio-economic position is associated with environmental hazards and poor housing conditions.10,11 To our knowledge, environmental exposures have not been considered in analyses of the influence of single parenthood on health outcomes in children until now.

The aim of this study was therefore to analyse the impact of both socio-economic and environmental factors on the association between single parenthood and adverse child health outcomes in Germany.

Methods

Study population

Three cross-sectional surveys were performed from 2004 to 2007 within the framework of the health monitoring units in Bavaria, Germany.12 The surveys were coupled to the compulsory pre-school examination in three rural and three urban regions. In all three rural and in two smaller urban study regions, a complete survey was performed. In the largest urban study region, Munich, performing a complete survey was not feasible, but data were instead collected in pre-defined city districts to obtain a representative sample of the resident population. In each survey, parents of children aged 5–7 years were asked to fill in a self-administered questionnaire. Informed written consent was obtained from all parents. The surveys were approved by the local ethics committee. Data on 19 039 children (47% female) were collected. Response rates were 78% (n = 6350, first survey 2004/05), 73% (n = 6206, second survey 2005/06) and 75% (n = 6483, third survey 2006/07). A single-parent family was defined as one parent living with the children without any partner. The classification as single-parent family was based on information on marital status, living together with a partner, number of adults in the household and the answer to the question ‘Are you a single parent?’ Couple families were defined as families with both parents including step parent living together. Cases with missing or incomplete information on family type (2.7%, n = 511) were excluded from analyses. Those 122 cases (0.6%) with no information whether the mother or father was the single parent were excluded. The small number of single fathers (0.4%, n = 79) were different regarding socio-demographic characteristics (data not shown). Therefore, the analyses focused on single-mother families. Children with missing values for sex, maternal education, traffic load and perceived environmental exposure were excluded from analyses. The final dataset for analyses comprised 17 218 children (90% of initial study population). In single-mother families, the questionnaires were completed almost exclusively by the mother alone (99%). In couple families, the majority of the questionnaires were completed by the mothers alone (62%) or by mothers and fathers together (31%).

Socio-economic and demographic factors

Data on family type, family size, nationality, maternal education, maternal employment status and income were collected. Maternal education was categorized into ‘high’ (qualification for university entrance), ‘middle’ (upper secondary school certificate) and ‘low’ (lower or no secondary school certificate). Maternal occupation was assessed as part- or full-time working with at least 15 h/week, marginally employed with <15 h/week or vocational training, not in labor force (e.g. housewife) or unemployed.

Household equivalent income was calculated on the basis of the monthly household net income as disposable income after taxes and social transfers, weighted according to age and number of household members using the weighting factors of the Organization for Economic Co-operation and Development-modified scale.13 Sixty per cent of the median household equivalent income in Bavaria was defined as the threshold of poverty risk.14 Families were categorized according to household income into ‘relatively poor’ (<60% of median Bavarian income), ‘low-medium’ (60–100% of median Bavarian income) and ‘above average’ (>100% of median Bavarian income). As a significant proportion (48%) of the parents refused to indicate their household net income, a separate category ‘not indicated’ was included in the analyses to avoid selection bias.

Child health outcomes

To cover different aspects of health in the analyses, we chose parent-reported health as a global health parameter, overweight and asthma as two of the most common chronic physical health problems in children and the Strengths and Difficulties Questionnaire (SDQ) total difficulty score for considering children’s mental health.

Global child health status was evaluated by the parents on a 5-point Likert scale, identical to the German health interview and examination survey on children and adolescents.15 The answers were dichotomized as very good/good vs. medium, poor or very poor.

Weight and height were measured using standard calibrated stadiometers and calibrated digital scales. To define overweight, age and sex-specific cutoff values of the body mass index established by Cole et al.16 were used.

Asthma was defined according to the International Study of Asthma and Allergies in Childhood, considering the parental report on symptoms and physician’s diagnosis in the self-administered questionnaire.17 Mental health was assessed using the SDQ, a brief questionnaire to screen for child behavioural disorders in community samples.18 According to the cut-off scores recommended for parent-completed questionnaires,19 the total difficulty score was calculated out of four problem subscales and categorized as normal vs. borderline or abnormal.

Environmental factors

Perceived environmental quality was assessed with the following question used in the German Socio Economic Panel.10,11 ‘How strongly do you feel affected by the following environmental factors in your residential area: noise, air pollution, lack of accessible green spaces?’ Answers were given on a 5-point Likert scale (not at all, low, just tolerable, high or very high), which was reduced for the analysis to a 2-point scale (not at all, low, just tolerable vs. high or very high). If the annoyance due to at least two of the three environmental factors was perceived as high or very high by the parents, the perceived environmental quality in the neighbourhood was rated poor.

Traffic load at the place of residence was characterized by the parents by three variables: the kind of street the family lived by (e.g. main road, side road), frequency of truck traffic and traffic jam. Traffic jam and truck traffic were dichotomized by summarizing ‘almost the whole day’ and ‘several times per day’ to yes and ‘never’ and ‘rarely’ to no. Traffic load at the place of residence was defined as high when at least two of the three variables indicated a high traffic load.

Statistical analyses

Multivariate associations between health outcome and family type were examined using logistic regression analysis. As effect estimates, adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. In order not to violate the assumption of homogeneity of the sample, the study region was considered as a confounder in each model. As the effect of single parenthood on health might be mediated by socio-economic factors or differences in environmental exposures, we chose an hierarchical approach.20 Logistic regression models were fitted on each health outcome adding socio-economic factors in Model 1, environmental factors in Model 2 and both in Model 3, all stratified for sex. To avoid multicollinearity, the independent variables were tested for correlation before inclusion into the model. Thus, only maternal education and household income were considered as independent socio-economic factors in multivariate analysis. All analyses were adjusted for age. Significant interactions between independent variables were considered with interaction terms in the models. In sensitivity analyses, potential differences between unmarried and divorced single mothers, and the confounding effect of child’s nationality were assessed. Additionally, multiple imputation of missing values of household income was applied instead of the category ‘not indicated’. All statistical analyses were performed using the SAS software package version 9.2 (SAS Institute Inc., Cary, NC, USA).

Results

Characteristics of single mother vs. couple families

Demographic and socio-economic statistics of single-mother families vs. couple families are given in table 1. Of the 17 218 children, 10% lived in single-mother families. Single mothers had a lower level of education and a higher rate of unemployment. One third of single mothers had a household income below the poverty threshold. Single-mother families were more often exposed to adverse physical environmental conditions (table 1). Furthermore, unmarried and divorced single mothers differed in some socio-economic characteristics: divorced single mothers had more often two or more children compared with unmarried single mothers (61% vs. 32%), a high level of education (26% vs. 23%), a slightly higher unemployment rate (18% vs. 16%) and worked less often part- or full time (53% vs. 61%). There was no difference in household income.

View this table:
Table 1

Socio-demographic and environmental characteristics of single-mother and couple families

CharacteristicSingle-mother family, % (n)Couple family, % (n)P2)
Sex (N = 17 218)0.20
    Girls45.8 (794)47.4 (7335)
    Boys54.2 (941)52.6 (8148)
Parent’s marital status (N = 17 117; 0.6% missing)
    Married95.9 (14 770)
    Divorced64.1 (1104)1.2 (190)
    Unmarried32.4 (559)2.7 (413)
    Widowed3.5 (60)0.1 (21)
Family size (N = 17 214; 0.02% missing)<0.0001a
    1 child47.3 (821)17.2 (2662)
    2 children39.1 (678)58.0 (8980)
    ≥3 children13.6 (236)24.8 (3837)
Nationality of the child (N = 17 163; 0.32% missing)0.05
    German91.6 (1585)90.4 (13 951)
    Non-German5.2 (90)6.7 (1034)
    German and other3.2 (55)2.9 (448)
Maternal education (N = 17 218)<0.0001a
    High25.0 (433)28.4 (4392)
    Middle34.6 (600)35.6 (5515)
    Low40.5 (702)36.0 (5576)
Maternal employment status (N = 16 746; 2.74% missing)<0.0001a
    Part- or full-time working (≥15 h/week)55.0 (943)33.9 (5093)
    Marginally employed (<15 h/week)13.6 (233)24.2 (3631)
    Not in labor force13.7 (235)35.4 (5318)
    Unemployed17.6 (302)6.6 (991)
Household equivalent income (N = 17 218)<0.0001a
    <60% of median31.5 (546)12.4 (1919)
    60 to <100% of median22.4 (388)23.9 (3701)
    ≥100% of median5.1 (88)15.3 (2363)
    Not indicated41.1 (713)48.4 (7500)
City/rural area (N = 16 713; 2.93% missing)<0.0001a
    City54.9 (927)41.5 (6236)
    Rural area45.1 (761)58.5 (8789)
Perceived environmental quality (N = 17 218)<0.0001a
    Low4.0 (70)2.4 (377)
    High96.0 (1665)97.6 (15 106)
Traffic load on residential road (N = 17 218)<0.0001a
    High18.3 (318)13.6 (2107)
    Low81.7 (1417)86.4 (13 376)
  • a: P < 0.05 after correction according to Bonferroni–Holms for multiple testing

Health characteristics of children from single mother vs. couple families

The prevalence of child health outcomes by family type is given in table 2. All adverse outcomes were more frequent in single-mother families. These differences between single-mother and couple families remained even if it was stratified between divorced and unmarried single mothers (data not shown).

View this table:
Table 2

Health characteristics of children from single-mother vs. couple families

Health characteristicSingle-mother family, % (n)Couple family, % (n)
Parent-reported health status: poor
    Boys (N = 9016)7.1 (67)5.4 (435)
    Girls (N = 8053)6.9 (54)4.2 (304)
Overweight
    Boys (N = 8622)14.6 (131)12.0 (930)
    Girls (N = 7718)15.8 (118)13.9 (971)
Asthmaa
    Boys (N = 6001)5.9 (37)4.7 (250)
    Girls (N = 5300)3.7 (19)2.0 (97)
SDQ total difficulty scoreb: borderline or abnormal
    Boys (N = 2783)19.4 (56)11.5 (287)
    Girls (N = 2580)10.9 (28)7.8 (174)
  • a: Data available only in the first and third survey

  • b: Data available only in the second survey

Considering the children altogether, characteristics of a disadvantaged social position (low maternal education, low household income) and a low environmental quality (perceived environmental exposures, high traffic load) were positively associated with impaired children’s health except for asthma (table 3).

View this table:
Table 3

Bivariate association of socio-demographic and environmental factors with the children’s health

Socio-demographic or environmental factorParent-reported health status: poor, OR (95% CI)Overweight, OR (95% CI)Asthma, OR (95% CI)SDQ total difficulty score: borderline or abnormal, OR (95% CI)
Low maternal educationa1.43 (1.19–1.71)1.92 (1.70–2.16)0.86 (0.67–1.11)2.54 (1.98–3.26)
Low household income (<60% of median)b2.35 (1.78–3.11)1.90 (1.58–2.27)1.23 (0.83–1.84)3.62 (2.49–5.26)
Low perceived environmental qualityc2.10 (1.52–2.90)1.63 (1.28–2.08)1.43 (0.83–2.48)2.61 (1.76–3.89)
High traffic load on residential roadd1.12 (0.93–1.36)1.48 (1.32–1.67)1.14 (0.87–1.50)1.98 (1.59–2.46)
  • a: Reference category: high maternal education; data not shown for the category ‘middle maternal education’

  • b: Reference category: ≥100% of median; data not shown for the category ‘60 to <100% of median income’

  • c: Reference category: high perceived environmental quality

  • d: Reference category: low traffic load on residential road

The multivariate associations of childhood health problems with single-mother families vs. couple families are summarized in table 4.

View this table:
Table 4

Association of health problems of children with single-mother families vs. couple families

Health outcomeModel 0, OR (95% CI)Model 1: + socio-economic factors, OR (95% CI)Model 2: + environmental factors, OR (95% CI)Model 3: + socio-economic and environmental factors, OR (95% CI)
Parent-reported health status: poor
    Boys (N = 9016)1.39 (1.06–1.82)1.28 (0.97–1.68)1.38 (1.05–1.80)a1.27 (0.96–1.67)a
    Girls (N = 8053)1.73 (1.28–2.33)1.53 (1.13–2.08)1.71 (1.27–2.32)1.53 (1.13–2.08)
Overweight
    Boys (N = 8622)1.23 (1.01–1.50)1.11 (0.90–1.36)1.21 (0.99–1.47)1.10 (0.90–1.35)
    Girls (N = 7718)1.17 (0.95–1.45)1.10 (0.89–1.36)1.15 (0.93–1.42)1.09 (0.88–1.35)
Asthmab
    Boys (N = 6001)1.30 (0.91–1.85)1.31 (0.91–1.89)1.29 (0.90–1.84)1.31 (0.91–1.88)
    Girls (N = 5300)1.90 (1.15–3.15)1.83 (1.09–3.06)1.90 (1.15–3.14)1.83 (1.09–3.07)
SDQ total difficulty scorec: borderline or abnormal
    Boys (N = 2783)1.90 (1.38–2.61)1.66 (1.20–2.31)1.82 (1.31–2.51)1.61 (1.15–2.24)
    Girls (N = 2580)1.58 (1.03–2.42)1.26 (0.81–1.95)1.56 (1.01–2.40)1.27 (0.82–1.98)
  • Model 0: adjusted for study region and age.

  • Model 1: adjusted for study region, age and socio-economic factors (maternal education, household income)

  • Model 2: adjusted for study region, age and environmental factors (perceived environmental quality, traffic load on residential road)

  • Model 3: adjusted for study region, age, socio-economic factors, and environmental factors

  • a: Adjusted for interaction term (perceived environmental quality × traffic load)

  • b: Data available only in the first and third survey

  • c Data available only in the second survey

Parent-reported health status of the child

Single mothers evaluated their child’s health more often as moderate to very poor than couple parents (table 4, Model 0). The impact of single parenthood on parent-reported health status decreased when adjusting for maternal education and household income (table 4, Model 1). Although the environmental factors investigated were associated with parent-reported health status, they did not alter the impact of single parenthood on child’s health (table 4, Model 2).

Overweight

Boys living with their single mothers were more often overweight compared with boys in couple families (table 4, Model 0). Adjusting for socio-economic parameters, the difference lost significance (table 4, Model 1). Although environmental factors were associated with overweight, adjusting for these characteristics did not change the increased OR of boys in single-mother families for overweight (table 4, Model 2).

Asthma

Girls from single mothers showed a higher odds of asthma (table 4, Model 0). Both maternal education and household income only slightly attenuated the association between family type and asthma in girls (table 4, Model 1). The environmental factors controlled for in Model 2 had no impact on the increased OR of asthma (table 4, Model 2).

Mental health: SDQ total difficulty score

Boys and girls of single mothers scored higher in the SDQ total difficulty score and thus were more often regarded as being at risk to develop mental health problems (table 4, Model 0). Adjusting for socio-economic factors reduced the effect estimates (table 4, Model 1), whereas adjusting for environmental factors changed the OR only marginally (table 4, Model 2).

In summary, adjusting for maternal education and household equivalent income as characteristics of social position attenuated the strength of the association of family type with physical and mental child’s health. Simultaneous adjustment for characteristics of the physical environment did not alter the differences between children with single mothers and those with couple families (table 4, Model 3), although environmental factors were associated with most outcomes investigated.

In sensitivity analyses, additional adjustment for child’s nationality as potential confounder did not alter the effect estimates. There were also no differences in the effect estimates if multiple imputation of missing values of the income variable was applied instead of using the category ‘not indicated’ (data not shown).

Discussion

In this study, we could identify increased health risks of children with single mothers compared with couple families. Adjusting for socio-economic factors decreased the strength of the associations of poor parent-reported health status, overweight and SDQ total difficulty score on the one hand and family type on the other hand. We found poorer environmental quality at the place of residence of single-mother families and an association of the environmental factors studied with several health outcomes in accordance with the fact that physical environmental factors are known to exert a strong influence on health.21,22 However, adjusting for these environmental factors did not alter the association of increased health risks of children with family type. To our knowledge, this is the first study on this topic including characteristics of the built environment.

We found that the influence of socio-economic factors on the adverse effect of single parenthood differed between the health outcomes investigated. As it has been previously shown in USA, single mothers assessed the general health of their children significantly worse than couple parents.23 Although Bauman et al.23 investigated the cumulative effects of social risk factors in child health, we could demonstrate in our study that socio-economic factors had a significant impact on parent-reported heath status and could explain some of the differences found between single-mother and couple families.

Several recent studies from USA have shown higher childhood obesity prevalence in children with single mothers compared with children in couple families.2426 Furthermore, obesity and overweight in children were found to be associated with a low socio-economic status in USA and Germany.26,27 Analogous, we found an association of maternal education and household income with overweight, which could partly explain the increased risk of overweight in boys of single mothers. Previous studies have demonstrated the influence of the built environment on obesity.7 Although we also found an association of environmental factors with overweight, we could not confirm our assumption of an impact of characteristics of the physical environment on the association between single parenthood and overweight in children.

In previous studies, differences in socio-economic circumstances accounted for much of or even fully explained the increased behavioural, emotional, educational or psychiatric problems observed in children living with only one parent.14 Our findings confirm the influence of maternal education and household income on the adverse effect of single parenthood on children’s mental health.

Asthma is the leading chronic disease among children in industrialized countries.28 Victorino and Gauthier29 demonstrated recently in a large cross-sectional study in USA that children from single-mother families were more likely to have asthma compared with children with two biological parents even after adjusting for household income. In contrast, the association of single parenthood and chronic respiratory problems in children in a British study was largely accounted for by material hardship.2 In our study, socio-economic factors had no striking impact on the association of single parenthood with childhood asthma.

There has been increased evidence that air pollution contributes to the development of childhood asthma.6,9 In a recent prospective birth cohort study from The Netherlands, a significant association between asthma prevalence and traffic-related air pollution was found.8 On the other hand, asthma was not associated with traffic volumes on residential roadways other than freeways in California communities.30 In our study, traffic load on residential roads also had no impact on asthma prevalence and did not influence the relationship between family type and asthma. However, in contrast to the studies mentioned above, we did not measure the air pollutant concentrations and only relied on the parent-reported traffic load.

Clearly, our study has a number of limitations: the characterization of the built environment relied on parental reports. Therefore, we cannot exclude over-reporting of environmental exposures in case of children’s poor health. For noise annoyance, we could show in a subsample of our study population that parental report of noise annoyance due to traffic in the residential environment was highly correlated to objectively assessed traffic-related noise exposure using the city’s noise map.31 In addition, the duration of exposure to the environmental hazards was not known.

A further limitation of our study is that we were not able to differentiate between step-parents and biological parents. It has been shown that children living with step-parents have an increased risk to develop asthma,29 to suffer from behavioural and emotional problems1,32 and a higher rate of accidents.33 Furthermore, we did not have data to consider the duration of single parenthood, the cause or whether there was joint custody, which all might have an impact on the health of the child. But we differentiated between divorced and unmarried single mothers in sensitivity analysis and did not find substantial differences in the association of family type and child health.

Risk factors other than low income and maternal education that influence child health include parental mental health, low maternal social support, family dysfunction and poor parenting skills.29,34 In this study, we were not able to adjust for these aspects.

Finally, due to the cross-sectional design we investigated associations. Conclusions on causalities cannot immediately be drawn. The potential reverse causality in the association between single parenthood and children’s health has been discussed by Bauman et al.,23 but empirical data are still lacking.

The strength of our study is the large data set based on complete surveys resulting in a study sample representative for families in the rural and urban study regions. This sample enabled us to analyse for the first time in Germany the associations of family type with several physical and mental child health outcomes considering socio-economic and environmental factors.

Conclusion

The differences in health outcomes between children from single-mother families and couple families are only partly explained by socio-economic factors. Although single-mother families experienced more often poor environmental quality, which was associated with most of the health outcomes investigated, adjusting for these environmental factors did not modify the effect of single parenthood on children’s health. This suggests that the parental reported environmental characteristics of the built environment are not precise enough to analyse potential mediating effects.

Whether socio-economic and physical environment disadvantages contribute to adverse health of children with single mothers is a topic of great importance for public health policy. To further address the question of mediation and causality as well as potential reverse causality in the association between single parenthood and child health, longitudinal studies would be necessary.

Funding

The surveys were partly funded by the Bavarian State Ministry of the Environment and Public Health, Munich, Germany.

Conflict of interest: None declared.

Key points

  • Single parenthood has been identified as a risk factor for health problems in children. Whether material disadvantage explains increased health risks in children in single-parent families is still controversial.

  • The effects of housing conditions and environmental exposures in the residential area have not been studied yet.

  • In this study, maternal education and household income partly explain health differences in children in single-mother families vs. couple families.

  • Perceived environmental quality of the built environment did not mediate the effect of single parenthood on child health.

  • Children of single-mother families are a vulnerable group. Public health policy should especially address their living conditions.

Acknowledgements

The authors thank all parents for participating in the survey and Lana Hendrowarsito for excellent data management.

Appendix A1

GME Study Group of the first three surveys 2004–07: Bavarian Health and Food Safety Authority, Oberschleissheim and Munich (Gabriele Bolte, Hermann Fromme, Annette Heissenhuber, Lana Hendrowarsito, Martina Kohlhuber, Christine Mitschek, Gabriele Morlock, Michael Mosetter, Uta Nennstiel-Ratzel, Dorothee Twardella and Manfred Wildner); Health Authority of the District Office of Bamberg (Wiltrud Doerk, Rosemarie Sittig, Winfried Strauch and Heidi Thamm); Health Authority of the District Office of Guenzburg (Tatjana Friess-Hesse, Dagmar Rudolph, Roland Schmid and Gudrun Winter); Health Authority of the City Ingolstadt (Christine Gampenrieder, Margot Motzet, Elisabeth Schneider, Traudl Tontsch and Gerlinde Woelk); Department of Health and Environment, City of Munich (Sylvia Kranebitter, Heidi Mayrhofer, Gertraud Rohrhirsch and Brigitte Weise); Health Authority of the District Office of Schwandorf (Kornelia Baranek, Gitte Koch-Singer and Maximilian Kuehnel); Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilian-University Munich (Ladan Baghi and Ruediger von Kries); Bavarian State Ministry of the Environment and Public Health (Bernhard Liebl).

Footnotes

  • *The members of GME Study Group are provided in Appendix A1

References

View Abstract