Relative Age Within School Grade, Including Delayed and Accelerated School Start: Associations With Midlife Psychiatric Disorders, Suicide, and Alcohol- and Drug-Related Mortality.

Within a school grade, children who are young for grade are at increased risk of psychiatric diagnoses, but the long-term implications remain understudied, and associations with students who delay or accelerate entry underexplored. We used Norwegian birth cohort records (birth years: 1967-1976, n = 626,928) linked to records in midlife. On-time school entry was socially patterned; among those born in December, 23.0% of children in the lowest socioeconomic position (SEP) delayed school entry, compared with 12.2% among the highest SEP. Among those who started school on time, there was no evidence for long-term associations between birth month and psychiatric/behavioral disorders or mortality. Controlling for SEP and other confounders, delayed school entry was associated with increased risk of psychiatric disorders and mortality. Children with delayed school entry were 1.31 times more likely to die by suicide (95% confidence interval: 1.07, 1.61) by midlife, and 1.96 times more likely to die from drug-related death (95% confidence interval: 1.59, 2.40) by midlife than those born late in the year who started school on time. Associations with delayed school entry are likely due to selection, and results thus underscore that long-term health risks can be tracked early in life, including through school entry timing, and are highly socially patterned.

Impact of the Norwegian Agreement for a More Inclusive Working Life on diagnosis-specific sickness absence in young adults: a difference-in-difference analysis.

BACKGROUND: The Norwegian Agreement for a More Inclusive Working Life (the IA Agreement) aims to reduce sickness absence (SA) and increase work participation. Potential impacts of the IA Agreement have not been thoroughly evaluated. The study aimed to estimate the impact of the IA Agreement on musculoskeletal and psychological SA prevalence and duration among young adult men and women, and to identify whether the impact was modified by economic activity or SA grade. METHODS: Data from national registries were combined for 372,199 individuals born in Norway 1967-1976. ICPC-2 codes identified musculoskeletal (L) and psychological (P) diagnoses. A difference-in-difference method compared prevalence and mean duration of first SA > 16 days between 2000 and 2005 separately for men and women working in IA companies relative to non-IA companies. Analyses were adjusted for mean company size and stratified by economic activity and SA grade (full/graded). Average marginal change was calculated with 95% confidence intervals (CI). RESULTS: The impacts of the IA Agreement on SA prevalence were mixed as the direction and size of marginal changes varied according to diagnosis, gender, and economic activity. However, there was a general tendency towards reduced mean SA duration for both diagnosis groups, and in particular men with musculoskeletal SA (- 16.6 days, 95% CI -25.3, - 7.9). Individuals with full SA in IA companies had greater reductions in mean SA duration. Only the wholesale and retail economic activity indicated a beneficial contribution of the IA Agreement for both SA prevalence and duration, in both diagnoses and genders. CONCLUSIONS: Potential impacts of the IA Agreement on SA in young men and women varied according to diagnosis and economic activity. However, results indicated that the IA Agreement could reduce SA duration. Further research should identify reasons for gender and economic activity differences.

Work participation in young Norwegians: a 19-year follow up in a registry-based life-course cohort.

Aims: The study objectives were to provide a quantitative description of work participation among young adults, and to outline the relations between work participation and social, educational and health-related characteristics throughout the life-course. Methods: We collected data in several national registries for all 318,705 individuals born in Norway 1967-1971 who were national residents on 1 January 1993. The criterion for work was annual occupational income above the boundary which identifies the core workforce. We analysed associations between social, educational and health-related characteristics, and the number of years at work and the risk of never working during 19 years of follow-up (1993-2011; age 22-44 years). Results: The overall work participation was high, with a median of 14 years and a 0.074 risk of never working. Women worked fewer years than men (medians 11 v. 16 years) and had higher risk of never working (0.103 v. 0.047). Combined educational and health problems before 1993 had a strong influence on subsequent work participation. The educational gradient in risks of never working was considerably stronger for women than for men. Diagnostic groups of mental disorders had high risks of never working, ranging from affective (risk 0.150) and stress-related disorders (risk 0.163) to intellectual disability (risk 0.933). Conclusions: The complex problems characterising individuals with low work participation suggest that preventive measures should take sex into account and be targeted at social, educational and mental issues in early life, and focusing on identified vulnerable groups.

Maternal exposure to psychosocial job strain during pregnancy and behavioral problems in the 11-year-old children: a Danish cohort study.

Maternal psychosocial stress may impact child neurodevelopment, but little is known regarding psychosocial job strain. We hypothesized high psychosocial job strain during pregnancy was associated with behavioural problems in the 11-year-old children. Mothers in the Danish National Birth Cohort (1996-2002) were included if they worked, provided information on job strain [Karasek's model: high job strain (often job demand/seldom job control) and passive (seldom or sometimes job demands/seldom job control)] during early pregnancy. At the 11-year follow-up, children (N = 30,592), mothers (N = 30,993), and teachers (N = 12,810) responded to the Strength and Difficulties Questionnaire (SDQ), a screening tool for child behaviour. Scores for hyperactivity, conduct, emotional and peer problems were dichotomised [80% (no) vs. 20% (yes)] according to Danish norms (yes/no). Maternal job strain was not associated with behavioural problems with teachers as informants. When assessed by child or mother, high maternal job strain increased risk of child behavioural problems, but risks were more pronounced for mothers in passive jobs [maternal assessment of total difficulties/odds ratio (95% confidence interval): high strain-girls: 1.16 (0.97-1.40); boys: 1.24 (1.02-1.50). Passive girls: 1.43 (1.21-1.68); boys: 1.25 (1.05-1.49)]. This is one of the first studies on this topic. The different types of maternal job strain were partly associated with child behavioural problems at 11 years; more so if mothers worked in passive rather than the hypothesized high strain jobs. Findings showing dependency on informant could not only indicate unmeasured confounding or rater's bias, but also selection in the smaller numbers of teacher informants or different environments of interaction with the children.

Long-term sickness absence among young and middle-aged workers in Norway: the impact of a population-level intervention.

BACKGROUND: The study objective was to evaluate the impact of a population-level intervention (the IA Agreement) on the of one-year risk for long-term sickness absence spells (LSAS) among young and middle aged workers in Norway. METHODS: Using an observational design, we conducted a quasi-experimental study to analyse registry data on individual LSAS for all employed individuals in 2000 (n = 298,690) and 2005 (n = 352,618), born in Norway between 1976 and 1967. The intervention of interest was the tripartite agreement for a more inclusive working life (the IA Agreement). We estimated difference in pre-post differences (DID) in LSAS between individuals working in IA companies with the intervention and companies without, in 2000 and 2005. We used logistic regression models and present odds ratios (DID OR) with accompanying 95% CI. We stratified analyses by sex, industry and company size. RESULTS: We found no significant change in the overall risk of long-term sickness absence spells after implementing the intervention among young and middle aged workers. Stratified by sex, the intervention resulted in a slight decrease in LSAS risk among female workers (DID OR 0.93 (0.91-0.96)) while the intervention showed no impact among male workers (DID OR 1.01 (0.97-1.06)). We found that companies signing the IA Agreement were large (≥50 employees) and often within the manufacturing and health and social sectors. In large manufacturing companies, we found a reduction in LSAS, among workers both in companies with and without the intervention, resulting in no statistically significant impact of the IA intervention. In large health and social companies, we found an increase in LSAS among workers both in companies with and without the intervention. The increase was smaller among the workers in companies offering the IA intervention compared with workers in companies without, resulting in a positive impact of the IA intervention in the health and social industry. This impact was statistically significant only among female workers. CONCLUSIONS: The results indicate that the impact of the IA Agreement on the risk of long-term sickness absence spells varies considerably depending on sex and industry. These findings suggest that reducing LSAS may warrant industry-specific interventions.

Job satisfaction and mental health of Palestinian nurses with shift work: a cross-sectional study.

BACKGROUND: Shift work is associated with sleep disturbances, mental health problems, and job dissatisfaction. Disparities between male and female nurses in the effect of shift work on mental distress and job satisfaction have been scarcely studied. We aimed to examine differences between female and male nurses in the associations between shift work and job satisfaction and mental health. METHODS: In this cross-sectional study, male and female nurses were recruited to rate their job satisfaction on the Generic Job Satisfaction Scale and to complete the General Health Questionnaire (GHQ-30). Associations between shift work, mental distress, and satisfaction were estimated from χ2 tests and linear regression analyses using Stata/IC10. The study was approved by the ministry of health. Written informed consent was provided by all participants. FINDINGS: In 2012, we recruited 372 registered nurses from the Hebron governorate in the occupied Palestinian territory. 28 (8%) nurses were excluded, and the final sample (n=344) included 213 (62%) women and 131 (38%) men. 338 nurses rated their job satisfaction, and 309 nurses completed the GHQ-30. After adjusting for covariates, men with shift work reported significantly lower job satisfaction (ß-coefficient -3·3, 95% CI -6·2 to -0·5) than men with day schedules. Women with shift work reported significantly higher levels of mental distress (3·6, 95% CI 0·3 to 7·0) than women with day schedules. Distress was reported by more women than men, but this difference concerned only nurses working day shifts. No differences in job satisfaction associated with shift work was seen between men and women. We found no demonstrable interaction between sex and shift work for job satisfaction (ß-coefficient -1·6, 95% CI -4·4 to 1·2) or distress (-0·03, 95% CI -5·3 to 5·3). INTERPRETATION: Shift work was associated with low job satisfaction in male nurses and high distress in female nurses. Because the study had a cross-sectional design and both exposure and outcomes were measured using self-report, the results should be interpreted with caution. Further studies should investigate whether shift work affects the quality of patient care. FUNDING: The Norwegian Programme for Development, Research and Education (NUFU; NUFU pro x1 50/2002 and NUFUSM-2008/10232) and The National Norwegian State Education Loan Funds.

Animal farming and the risk of lymphohaematopoietic cancers: a meta-analysis of three cohort studies within the AGRICOH consortium.

OBJECTIVE: Animal farming entails a variety of potential exposures, including infectious agents, endotoxins and pesticides, which may play a role in the aetiology of lymphohaematopoietic cancers (LHCs). The aim of this study was to assess whether farming specific animal species is associated with the risk of overall LHC or its subtypes. METHODS: Data from three prospective cohort studies in the USA, France and Norway which are part of the Agricultural Cohort consortium and which collected information about animal farming and cancer were used. Analyses included 316 270 farmers and farm workers. Adjusted Cox models were used to investigate the associations of 13 histological subtypes of LHC (n=3282) with self-reported livestock (cattle, pigs and sheep/goats) and poultry (ever/never and numbers raised) farming. Cohort-specific HRs were combined using random-effects meta-analysis. RESULTS: Ever animal farming in general or farming specific animal species was not meta-associated with overall LHC. The risk of myeloid malignancies decreased with increasing number of livestock (p trend=0.01). Increased risk of myeloproliferative neoplasms was seen with increasing number of sheep/goats (p trend <0.01), while a decreased risk was seen with increasing number of livestock (p trend=0.02). Between cohorts, we observed heterogeneity in the association of type of animal farmed and various LHC subtypes. CONCLUSIONS: This large-scale study of three prospective agricultural cohorts showed no association between animal farming and LHC risk, but few associations between specific animal species and LHC subtypes were observed. The observed differences in associations by countries warrant further investigations.

Information bias of social gradients in sickness absence: a comparison of self-report data in the Norwegian Mother and Child Cohort Study (MoBa) and data in national registries.

BACKGROUND: Measurement error in self-report questionnaires is a common source of bias in epidemiologic studies. The study aim was to assess information bias of the educational gradient in sickness absence among participants in the Norwegian Mother and Child Cohort Study (MoBa), comparing self-report data with national register data. METHODS: MoBa is a national prospective cohort study. The present study included 49,637 participants, born 1967-1976, who gave birth 2000-2009. The highest completed education level was recorded in categories and as educational years. Sickness absence was defined as one or more spell lasting more than 16 days between pregnancy weeks 13 and 30. We computed sickness absence risk in mid-pregnancy in strata of education level. Associations between completed educational years and sickness absence were estimated as risk differences in binomial regression and compared between self-report and register data. In additional analyses, we aimed to explain discrepancies between estimates from the two data sources. RESULTS: The overall registry-based sickness absence risk was 0.478 and decreased for increasingly higher education in a consistent fashion, yielding an additive risk difference in association with one additional education year of - 0.032 (95% confidence interval - 0.035 to - 0.030). The self-report risk was lower (0.307) with a corresponding risk difference of only - 0.013 (95% confidence interval - 0.015 to - 0.011). The main explanation of the lower risk difference in the self-report data was a tendency for mothers in low education categories to omit reporting sickness absence in the questionnaire. CONCLUSIONS: A plausible explanation for the biased self-report association is complexity of the sickness absence question and a resulting educational gradient in non-response. As shown for sickness absence in mid-pregnancy in the present study, national registries could be a preferred alternative to self-report questionnaires.

The impact of completing upper secondary education - a multi-state model for work, education and health in young men.

BACKGROUND: Completing upper secondary education is associated with higher work participation and less health-related absence from work. Although these outcomes are closely interrelated, most studies focus on single outcomes, using cross-sectional designs or short follow-up periods. As such, there is limited knowledge of the long-term outcomes, and how paths for completers and non-completers unfold over time. In this paper, we use multi-state models for time-to-event data to assess the long-term effects of completing upper secondary education on employment, tertiary education, sick leave, and disability pension over twelve and a half years for young men. METHODS: Baseline covariates and twelve and a half years of follow-up data on employment, tertiary education, sick leave and disability pension were obtained from national registries for all males born in Norway between 1971 and 1976 (n =184951). The effects of completing upper secondary education (by age 23) were analysed in a multi-state framework, adjusting for both individual and family level confounders. All analyses were done separately for general studies and vocational tracks. RESULTS: Completers do better on a range of outcomes compared to non-completers, for both fields of upper secondary education, but effects of completion change over time. The largest changes are for tertiary education and work, with the probability of work increasing reciprocally to the probability of education. Vocational students are quicker to transfer to the labour market, but tend to have more unemployment, sick leave and disability, and the absolute effects of completion on these outcomes are largest for vocational tracks. However, the relative effects of completion are larger for general studies. CONCLUSION: Completing upper secondary education increases long-term work participation and lowers health-related absence for young men, but effects diminish over time. Studies that have used shorter follow-up periods could be overstating the negative effects of dropout on labour market participation. Multi-state models are well suited to analyse data on work, education and health-related absence, and can be useful in understanding the dynamic aspects of these outcomes.

Workplace aggression, psychological distress, and job satisfaction among Palestinian nurses: A cross-sectional study.

BACKGROUND: Nurses can be exposed to aggressive behavior from patients, patient's relatives, colleagues and visitors. PURPOSE: To determine the prevalence of workplace aggression among Palestinian nurses in the Hebron district and to examine cross-sectional associations between exposure to workplace aggression and the occurrence of psychological distress and job satisfaction. METHODS: Of 372 nurses eligible for the study, 343 were included (response rate of 92.2%). The sample comprised 62% females and 38% males. The participants responded to questions about their socio-demographic status, workplace aggression (WHO questionnaires), psychological distress (General Health Questionnaire, GHQ-30), and job satisfaction (Generic Job Satisfaction Scale). RESULTS: Ninety-three (27.1%) of the respondents reported exposure to workplace aggression of any kind. Seventeen (5%) reported exposure to physical aggression, 83 (24.2%) reported exposure to verbal aggression, and 25 (7.3%) reported exposure to bullying. The patients and the patients' relatives were the main sources of physical and verbal aggression, whereas colleagues were the main source of bullying. Males reported a higher prevalence of bullying than females. Younger nurses reported a higher prevalence of exposure to physical aggression, verbal aggression and bullying. Verbal aggression was associated with more psychological distress. Bullying was associated with lower job satisfaction. CONCLUSIONS: More than a quarter of the nurses reported that they had been subject to some sort of aggression at the workplace. Verbal aggression was associated with higher psychological distress. Workplace bullying was associated with lower job satisfaction. Increased awareness and preventive measures to address this problem among health care workers are warranted.

Selection bias due to parity-conditioning in studies of time trends in fertility.

BACKGROUND: Studies of couple fertility over time have often examined study populations with broad age ranges at a cross-section of time. An increase in fertility has been observed in studies that followed episodes of fertility events either prospectively among nulliparous women or retrospectively among parous women. Fertility has a biological effect on parity. If defined at a cross-section of time, parity will also be affected by year of birth, and thus becomes a collider. Conditioning (stratifying, restricting, or adjusting) on a collider may cause selection bias in the studied association. METHODS: A study with prospective follow-up was taken as the model to assess the validity of fertility studies. We demonstrate the potential for selection bias using causal graphs and nationwide birth statistics and other demographic data. We tested the existence of parity-conditioning bias in data including both parous and nulliparous women. We also used a simulation approach to assess the strength of the bias in populations with prior at-risk cycles. Finally, we evaluated the potential for selection bias due to conditioning on parity in various sampling frames. RESULTS: Analyses indicate that the observed increase in fertility over time can be entirely explained by selection bias due to parity-conditioning. CONCLUSION: Heterogeneity in fertility and differential success in prior at-risk cycles are the ultimate factors behind the selection bias. The potential for selection bias due to parity-conditioning varies by sampling frame. A prospective multidecade study with representative sampling of birth cohorts and follow-up from menarche to menopause would bypass the described bias.

Airway inflammation and ammonia exposure among female Palestinian hairdressers: a cross-sectional study.

OBJECTIVES: Little is known about the working conditions and airway inflammation in hairdressers in Palestine. We aimed to investigate if hairdressers in Palestine have a higher level of airway inflammation as compared to a control group. We also assessed the hairdressers' physical working conditions and exposure to ammonia gases at the hair salons. Lastly, we investigated the association between ammonia levels and inflammation markers in the airways and the blood. METHODS: Our study participants were 33 non-smoking hairdressers (aged 19-50 years) and 35 non-smoking control subjects (aged 18-49 years). Both groups answered a questionnaire on respiratory symptoms, and performed lung function and exhaled nitric oxide (eNO) tests. Blood and sputum samples were collected from all participants and air concentration levels of ammonia were measured in 13 salons. RESULTS: Hairdressers had a higher level of sputum neutrophil count (absolute numbers/mg sputum (median (25th-75th centiles)) compared to controls, 376 (183-980) and 182 (96-358), respectively. Hairdressers also had significantly elevated eNO and blood C reactive protein (CRP) levels compared to the control subjects, controlled for age and body mass index. Exposure measurements showed that the hairdressers in salons with scarce ventilation were exposed to ammonia concentration, ranging from 3 to 61 mg/m(3). CONCLUSIONS: Compared to unexposed controls, the hairdressers had signs of neutrophilic airway inflammation, higher eNO levels and higher CRP. The hairdressers were exposed to high concentrations of ammonia from hairdressing chemicals and their working conditions were unsatisfactory.

Maternal Sick Leave Due to Psychiatric Disorders Following the Birth of a Child With Special Health Care Needs.

OBJECTIVE: Child-related stress following the birth of a child with special health care needs (SHCN) can take a toll on parental health. This study examined how the risk of sick leave due to psychiatric disorders (PD) among mothers of children with SHCN compares with that of mothers of children without SHCN during early motherhood. METHODS: Responses from 58,532 mothers participating in the Norwegian Mother and Child Cohort Study were linked to national registries and monitored for physician-certified sick leave from the month of their child's first birthday until the month of their child's fourth birthday. RESULTS: As compared with mothers of children without SHCN, mothers of children with mild and moderate/severe care needs were at substantial risk of a long-term sick leave due to PD in general and due to depression more specifically. CONCLUSIONS: Extensive childhood care needs are strongly associated with impaired mental health in maternal caregivers during early motherhood.

The gender gap in sickness absence from work and the influence of parental absence on offspring absence 15 years later: register-based cohort of Norwegians born in 1974-1976.

BACKGROUND: Women have shown consistently higher levels of sickness absence from work in comparison to men, but explanations for this gender gap have not been completely understood. Life-course studies suggest that health and health-related social benefits in adult age are influenced by early life experiences. We aimed to estimate intergenerational associations with a 15-year time gap between parents' and offspring sickness absences, pursuing the hypothesis that this parental influence would have a stronger impact for women than for men. METHODS: All persons born alive between 1974 and 1976 in Norway were followed up in several national registries. Employed persons considered to be at risk of sickness absence and also with parents at risk of sickness absence (n = 78,878) were followed in the calendar year of their 33(rd) birthday with respect to spells lasting >16 days. The probability of one or more spells during this year constituted the one-year risk under study. Additive risk differences in association with an exposure (parental sickness absence 15 years earlier) were estimated in a binomial regression analysis. The estimates were adjusted for parental socioeconomic factors. RESULTS: The 1-year sickness absence risk was higher for women (30.4%) than for men (12.3%). The crude risk differences between those exposed and those unexposed to parental sickness absence were similar in percentage points (PP) for women (3.8; 95% confidence interval (CI) 2.6 to 4.9) and men (3.8; 95% CI 2.9 to 4.6). The risk differences were moderately attenuated after adjustment for parental education and father's income to 3.4 PP (2.2 to 4.5) for women and 2.8 PP (2.0 to 3.7) for men. Male absence was more strongly associated with the father's than with the mother's sickness absence, while associations for women were stronger for the same diagnostic groups as their parents. CONCLUSIONS: Parental sickness absence was moderately associated with sickness absence in the next generation. Bias from unmeasured confounders cannot be entirely dismissed. Contrary to our hypothesis, associations were not stronger for women than for men. If parental sickness absence has a long-term causal effect, preventive measures could have an impact over generations.

The association of high birth weight with intelligence in young adulthood: a cohort study of male siblings.

We aimed to explore why, in population studies, the positive association between normal-range birth weight and intelligence becomes negative at the highest birth weights. The study population comprised 217,746 Norwegian male singletons born at term between 1967 and 1976. All had data on birth weight and intelligence quotient (IQ) score at the time of military conscription; 137,574 had data on sibling birth weights; and 62,906 had data on male sibling birth weights. We estimated associations between birth weight and IQ score by ordinary least squares regression for the total study population and by fixed-effects regression for comparisons of brothers. The crude mean IQ score was 1.2 points (95% confidence interval (CI): 0.3, 2.2) lower for those with birth weights of 5,000 g or more compared with the reference group (with birth weights of 4,000-4,499 g). This difference leveled off to 0.0 (95% CI: -0.8, 0.9) in multivariable ordinary least squares regression and reversed to 2.2 points (95% CI: 0.3, 4.2) higher in fixed-effects regression. Results differed mainly because, at a given birth weight, participants who had a sibling with macrosomia had a lower mean IQ score. Nevertheless, within families with 1 or more macrosomic siblings, as in other families, men with higher birth weights tended to have higher IQ scores. Thus, a family-level confounder introduces a cross-level bias that cannot be detected in individual-level studies. We suggest ways in which future studies might elucidate the nature of this confounder.

Employment trends during preschool years among mothers of term singletons born with low birth weight.

Children born at term with low birth weight (LBW) are regarded growth restricted and are at particular risk of adverse health outcomes requiring a high degree of parental participation in the day-to-day care. This study examined whether their increased risk of special health care needs compared to other children may influence mothers' opportunities for participation in the labor market at different times after delivery. Data from 32,938 participants in the population-based Norwegian Mother and Child Cohort Study with singleton children born at term in 2004-2006 were linked to national registers in order to investigate the mothers' employment status when their children were 1-3 years in 2007 and 4-6 years in 2010. Children weighing less than two standard deviations below the gender-specific mean were defined as LBW children. Although not significantly different from mothers of children in the normal weight range, mothers of LBW children had the overall highest level of non-employment when the children were 1-3 years. At child age 4-6 years on the other hand, LBW was associated with an increased risk of non-employment (RR 1.39: 95 % CI 1.11-1.75) also after adjustment for factors associated with employment in general. In accordance with employment trends in the general population, our findings show that while mothers of normal birth weight children re-enter the labor market as their children grow older, mothers of LBW children born at term participate to a lesser extent in paid employment and remain at levels similar to those of mothers with younger children.

The impact of a child's special health care needs on maternal work participation during early motherhood.

BACKGROUND: Many women temporarily reduce work hours or stop working when caring for small children. However, mothers of children with special health care needs may face particular challenges balancing childrearing responsibilities and employment demands. This study examines how the work participation among mothers of children with special health care needs compares with that of mothers in general during early motherhood, focusing in particular on the extent of the child's additional health care needs. METHODS: By linkage of the population-based Norwegian Mother and Child Cohort Study with national registers on employment, child health care needs, and social background factors, 41,255 mothers employed prior to childbirth were followed until child age 3 years to investigate associations between the child's care needs and mother's dropping out of employment. RESULTS: In total, 16.3% of the formerly employed mothers were no longer employed at child age 3 years. Mothers of children with mild care needs did not differ from mothers in general, whereas mothers of children with moderate [Risk Ratio (RR) 1.45; 95% confidence interval (CI) 1.17, 1.80] and severe care needs [RR 2.19; 95% CI 1.67, 2.87] were at substantial risk of not being employed at follow-up. The impact of the child's health care needs remained strong also after adjusting for several factors associated with employment in general. CONCLUSIONS: Extensive childhood health care needs are associated with reduced short-term employment prospects and remain a substantial influence on mothers' work participation during early motherhood, irrespective of other important characteristics associated with maternal employment.

Impact of aerobic fitness on musculoskeletal sickness absence 5-15 years later: a cohort study of 227,201 male Norwegian employees.

OBJECTIVES: The aim of the study was to estimate associations between aerobic fitness among men at age 18-19 years and work absence due to musculoskeletal sickness 5-15 years later. METHODS: All 321,975 men born between 1967 and 1976 in Norway were identified and followed up in several national registers. Men who completed an aerobic fitness test at military conscription during 1985-1995 (N=227,201) were followed from 2000 through 2003 with respect to a first musculoskeletal absence. Cox regression was conducted to estimate HRs between aerobic fitness (high, medium, poor) and musculoskeletal absence. RESULTS: A total of 26,061 men had a musculoskeletal absence (absolute risk 0.115). Absence was associated with fitness level. Associations were confounded by other conscript characteristics (intellectual capacity, body mass index, musculoskeletal condition) and parental education level and were restricted to non-injury absence. With high fitness as reference, the adjusted non-injury HR estimates were 1.18 (95% CI 1.12 to 1.24) and 1.39 (1.31 to 1.47) for medium and poor fitness, respectively. Poor fitness men were more likely to achieve low educational attainment and employment in high-absence industries and enterprises. The impact of intellectual capacity and parental education level on absence was considerably larger than the effect from fitness. A subset analysis with fitness data of better quality yielded moderately stronger associations. CONCLUSIONS: Aerobic fitness among conscripts was moderately associated with non-injury musculoskeletal absence 5-15 years later. However, the overall impact of intellectual capacity and parental education appears to be greater than that of aerobic fitness.

Social inequalities in road traffic deaths at age 16-20 years among all 611,654 Norwegians born between 1967 and 1976: a multilevel analysis.

BACKGROUND: Road traffic injury is a major cause of death among youths. AIMS: To estimate mortality differences in family socioeconomic position (SEP) and municipal disadvantage level. METHODS: Data on all Norwegians born in 1967-76, gathered from national registries, were linked by a unique national identification number. The 611 654 participants were followed-up for 5 years from age 16 years. Parental education level, father's income level, and proportion of high-income earners in the municipality served as SEP indicators. Associations between SEP and road traffic deaths were analysed by multilevel Poisson regression. Results Road traffic deaths (n=676, rate 22.2 per 100 000 person-years) constituted a major cause of death, of which 91.9% were motor vehicle occupants. SEP distributions differed according to gender and type of motor vehicle crash (collision, non-collision). There was an inverse relationship between municipal proportions of high-income earners and mortality (population attributable fraction (PAF) 0.43, 95% CI 0.30 to 0.53) in all categories of gender-specific crash types. Family SEP gradients were not found except for male non-collision deaths, where increasing mortality was found in association with decreasing parental education level (PAF 0.94, 95% CI 0.59 to 0.99) and increasing paternal income (PAF 0.25, 95% CI 0.06 to 0.40). CONCLUSION: The different SEP patterns for road traffic deaths across gender and motor vehicle crash type illustrate that heterogeneity of social inequalities in health can be found even within narrow age bands and for similar causes of death.

Life expectancy and cause of death in men examined at medical check-ups in 1964.

BACKGROUND: The purpose of the study was to determine the associations between blood pressure, body mass index and smoking habits, recorded at routine health check-ups with the occupational health officer, and life expectancy and cause-specific mortality through several decades. MATERIAL AND METHODS: Participants in the Linseed Oil Study were followed from 1967 through 2005 with respect to total and cause-specific mortality in the Cause of Death Registry. The population studied consisted of 15,934 men who were born between 1905 and 1914 and were in work in 1967. The analyses used various multivariate regression methods. RESULTS: A total of 15,535 participants (97.5%) had died, and the average age at death was 76.6 years (SD 9.1). Blood pressure, body mass index and cigarette smoking were related to the age of death and mortality due to cardiovascular disease, lung cancer and respiratory system diseases. High systolic blood pressure (≥ 160 mm) was associated with a life-expectancy shortening of 5 years, 15 cigarettes daily with 3.5 years and a confirmed elevated sedimentation rate with a 3.3 year shortening of life expectancy. The excess mortality persisted throughout the follow-up period. The association with blood pressure gradually lessened, while the association with smoking and body mass index did not change over time. The association with smoking was weaker than in most early studies. INTERPRETATION: The results of routine health check-ups in the occupational health service can predict lost years of life through several decades.