| 1. |
- Aradhya, Siddartha, et al.
(author)
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Maternal age and the risk of low birthweight and pre-term delivery : a pan-Nordic comparison
- 2022
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 52:1, s. 156-164
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Journal article (peer-reviewed)abstract
- Background: Advanced maternal age at birth is considered a risk factor for adverse birth outcomes. A recent study applying a sibling design has shown, however, that the association might be confounded by unobserved maternal characteristics.Methods: Using total population register data on all live singleton births during the period 1999–2012 in Denmark (N = 580 133; 90% population coverage), Norway (N = 540 890) and Sweden (N = 941 403) and from 2001–2014 in Finland (N = 568 026), we test whether advanced maternal age at birth independently increases the risk of low birthweight (LBW) (<2500 g) and pre-term birth (<37 weeks gestation). We estimated within-family models to reduce confounding by unobserved maternal characteristics shared by siblings using three model specifications: Model 0 examines the bivariate association; Model 1 adjusts for parity and sex; Model 2 for parity, sex and birth year.Results: The main results (Model 1) show an increased risk in LBW and pre-term delivery with increasing maternal ages. For example, compared with maternal ages of 26–27 years, maternal ages of 38–39 years display a 2.2, 0.9, 2.1 and 2.4 percentage point increase in the risk of LBW in Denmark, Finland, Norway and Sweden, respectively. The same patterns hold for pre-term delivery.Conclusions: Advanced maternal age is independently associated with higher risk of poor perinatal health outcomes even after adjusting for all observed and unobserved factors shared between siblings.
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| 2. |
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| 3. |
- Beckley, Amber L., et al.
(author)
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Association of height and violent criminality : results from a Swedish total population study
- 2014
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 43:3, s. 835-842
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Journal article (peer-reviewed)abstract
- Background: Violent criminality is at least moderately heritable, but the mechanisms behind this remain largely unexplained. Height, a highly heritable trait, may be involved but no study has estimated the effect of height on crime while simultaneously accounting for important demographic, biological and other heritable confounders. Methods: We linked nationwide, longitudinal registers for 760 000 men who underwent mandatory military conscription from 1980 through 1992 in Sweden, to assess the association between height and being convicted of a violent crime. We used Cox proportional hazard modelling and controlled for three types of potential confounders: physical characteristics, childhood demographics and general cognitive ability (intelligence). Results: In unadjusted analyses, height had a moderate negative relationship to violent crime; the shortest of men were twice as likely to be convicted of a violent crime as the tallest. However, when simultaneously controlling for all measured confounders, height was weakly and positively related to violent crime. Intelligence had the individually strongest mitigating effect on the height-crime relationship. Conclusions: Although shorter stature was associated with increased risk of violent offending, our analyses strongly suggested that this relationship was explained by intelligence and other confounding factors. Hence, it is unlikely that height, a highly heritable physical characteristic, accounts for much of the unexplained heritability of violent criminality.
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| 4. |
- Björkenstam, Emma, et al.
(author)
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Juvenile delinquency, social background and suicide-a Swedish national cohort study of 992 881 young adults
- 2011
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 40:6, s. 1585-1592
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Journal article (peer-reviewed)abstract
- Background As the suicide rates in young adults do not show a clear decline, it is important to elucidate possible risk factors. Juvenile delinquency has been pointed out as a possible risk behaviour. Methods This register-based cohort study comprises the birth cohorts between 1972 and 1981 in Sweden. We followed 992 881 individuals from the age of 20 years until 31 December 2006, generating 10 210 566 person-years and 1482 suicides. Juvenile delinquency was defined as being convicted of a crime between the ages of 15 and 19 years. Estimates of risk of suicide were calculated as incidence rate ratio (IRR) with 95% confidence intervals (CIs) using Poisson regression analysis with adjustment for potential confounding by their own and their parents' mental illness or substance abuse, parental education, single parenthood, social assistance, adoption and foster care. Results Among females, 5.9%, and among males, 17.9%, had at least one conviction between the ages 15 and 19 years. In the fully adjusted model, females with one conviction had a suicide risk of 1.7 times higher (95% CI 1.2-2.4), the corresponding IRR for men was 2.0 (95% CI 1.7-2.4) and 5.7 (95% CI 2.5-13.1) and 6.6 (95% CI 5.2-8.3), for women and men with five or more convictions. The effect of severe delinquency on suicide was independent of parental educational level. Conclusions This study supports the hypothesis that individuals with delinquent behaviour in late adolescence have an increased risk of suicide as young adults. Regardless of causality issues, repeated juvenile offenders should be regarded by professionals in health, social and correctional services who come into contact with this group as a high-risk group for suicide.
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| 5. |
- Cozzani, Marco, et al.
(author)
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The cognitive development from childhood to adolescence of low birthweight children born after medically assisted reproduction-a UK longitudinal cohort study
- 2021
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 50:5, s. 1514-1523
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Journal article (peer-reviewed)abstract
- Background: Previous research has documented that children conceived through medically assisted reproduction (MAR) are at increased risk of poor birth outcomes, such as low birthweight (LBW), which are risk factors for stunted longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds which could compensate for the negative effects of being born LBW. Previous studies have not analysed whether the negative effects of LBW are attenuated among MAR conceived children.Methods: We draw on the UK Millennium Cohort Study (sweeps 1–6) which contains a sub-sample of (N = 396) MAR-conceived children. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR-conceived low birthweight (MAR LBW); MAR-conceived non-low birthweight (MAR NLBW); naturally conceived low birthweight (NC LBW); naturally conceived non-low birthweight (NC NLBW). We estimate the two following linear regression models for each sweep: (i) a baseline model to examine the unadjusted association between cognitive development and low birthweight by mode of conception; and (ii) a model adjusted by socio-demographic family characteristics.Results: In baseline models, MAR LBW children [age 3: β = 0.021, 95% confidence interval (CI): -0.198, 0.241; age 5: β = 0.21, 95% CI: 0.009, 0.418; age 7: β = 0.163, 95% CI: -0.148, 0.474; age 11: β = 0.003, 95% CI: -0.318, 0.325; age 14: β = 0.156, 95% CI: -0.205, 0.517], on average perform similarly in cognitive ability relative to NC NLBW at all ages, and display higher cognitive scores than NC LBW children until age 7. When we account for family characteristics, differences are largely attenuated and become close to zero at age 14.Conclusions: Despite the higher incidence of LBW among MAR compared with NC children, they do not seem to experience any disadvantage in their cognitive development compared with naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born to socioeconomically advantaged parents.
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| 6. |
- Dekhtyar, Serhiy, et al.
(author)
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Childhood school performance, education and occupational complexity : a life-course study of dementia in the Kungsholmen Project
- 2016
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 45:4, s. 1207-1215
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Journal article (peer-reviewed)abstract
- Background: Cognitive reserve hypothesis predicts that intellectually demanding activities over the life course protect against dementia. We investigate if childhood school performance remains associated with dementia once education and occupational complexity are taken into account. Methods: A cohort of 440 individuals aged 75+ from the Kungsholmen Project was followed up for 9 years to detect dementia. To measure early-life contributors to reserve, we used grades at age 9-10 extracted from the school archives. Data on formal education and occupational complexity were collected at baseline and first follow-up. Dementia was ascertained through comprehensive clinical examination. Cox models estimated the relationship between life-course cognitive reserve measures and dementia. Results: Dementia risk was elevated [hazard ratio (HR): 1.54, 95% confidence interval (CI): 1.03 to 2.29] in individuals with low early-life school grades after adjustment for formal educational attainment and occupational complexity. Secondary education was associated with a lower risk of dementia (HR: 0.72, 95% CI: 0.50 to 1.03), although the effects of post-secondary and university degrees were indistinguishable from baseline. Occupational complexity with data and things was not related to dementia. However, an association was found between high occupational complexity with people and dementia, albeit only in women (HR: 0.39, 95% CI: 0.14 to 0.99). The pattern of results remained unchanged after adjustment for genetic susceptibility, comorbidities and depressive symptoms. Conclusion: Low early-life school performance is associated with an elevated risk of dementia, independent of subsequent educational and occupational attainment.
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| 7. |
- Ericsson, Malin, et al.
(author)
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Life-course socioeconomic differences and social mobility in preventable and non-preventable mortality : a study of Swedish twins
- 2019
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In: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:5, s. 1701-1709
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Journal article (peer-reviewed)abstract
- BackgroundDespite advances in life expectancy, low socioeconomic status is associated with a shorter lifespan. This study was conducted to investigate socioeconomic differences in mortality by comparing preventable with non-preventable causes of death in 39 506 participants from the Swedish Twin Registry born before 1935.MethodsChildhood social class, own education, own social class and social mobility were used as separate indicators of socioeconomic status. These data were linked to the Swedish Cause of Death Register. Cause of death was categorized as preventable or non-preventable mortality according to indicators presented in the Avoidable Mortality in the European Union (AMIEHS) atlas. Using Cox proportional hazard models, we tested the association between the socioeconomic measures and all-cause mortality, preventable mortality and non-preventable mortality. Additional co-twin control analyses indicated whether the associations reflected genetic confounding.ResultsThe social gradient for mortality was most prominent for the adult socioeconomic measures. There was a social gradient in both preventable mortality and non-preventable mortality, but with an indication of a moderately stronger effect in preventable causes of death. In analyses of social mobility, those who experienced life-time low socioeconomic status (SES) or downward social mobility had an increased mortality risk compared with those with life-time high SES and upward social mobility. Adjustments for genetic confounding did not change the observed associations for education, social class or social mobility and mortality. In the co-twin control analyses of reared-apart twins, the association between childhood social class and mortality weakened, indicating possible genetic influences on this association.ConclusionsOur results indicate that there is an association between low adult socioeconomic status and increased mortality independent of genetic endowment. Thus, we do not find support for indirect social selection as the basis for mortality inequalities in Sweden
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| 8. |
- Gao, Menghan, et al.
(author)
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Associations of perinatal characteristics with endometriosis : a nationwide birth cohort study
- 2020
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 49:2, s. 537-547
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Journal article (peer-reviewed)abstract
- BACKGROUND: Perinatal characteristics are associated with subsequent risk of several chronic diseases. Previous studies regarding endometriosis were based on small samples and retrospective data and were limited by unmeasured confounding bias, leading to conflicting and inconclusive findings. We investigated the associations of maternal and birth characteristics with risk of endometriosis among Swedish women of reproductive age. METHODS: This total-population register-based cohort study consisted of 628 312 singleton women born in Sweden between 1973 and 1987, who were followed for diagnosed endometriosis from age 15 years until the end of 2012. Multivariable Cox regression was applied to examine associations with perinatal characteristics. Residual unmeasured confounding was assessed through within-family and E-value analyses. RESULTS: During follow-up, 8262 women received an endometriosis diagnosis. There were clear dose-response/linear associations of endometriosis with lower maternal education, endometriosis in the mother [adjusted hazard ratio (aHR): 2.24, 95% confidence interval (CI): 2.04-2.46], maternal smoking during pregnancy (aHR: 1.18, 95% CI: 1.04-1.33 for moderate smoker and aHR: 1.36, 95% CI: 1.18-1.57 for heavy smoker vs non-smoker), lower birthweight, and lower birthweight-for-gestational age (aHR: 0.93 per standard deviation increase, 95% CI: 0.91-0.95). Within-family and E-value analyses suggested that these perinatal characteristics are robust predictors of the incidence of endometriosis. We also found that an estimated 26% of the association between maternal smoking and early-onset endometriosis could be explained by birthweight-for-gestational age. CONCLUSION: This study finds support for fetal origins of endometriosis, in that exposure to adverse environment or restricted development during the perinatal period may increase the risk. Further research is needed to provide an understanding of the underlying mechanisms.
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| 9. |
- Gao, Menghan, et al.
(author)
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Exposure to out-of-home care in childhood and adult all-cause mortality : a cohort study
- 2017
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 46:3, s. 1010-1017
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Journal article (peer-reviewed)abstract
- Background: Children placed in out-of-home care (OHC) have exceedingly high rates of health problems. Their poor health tends to persist across adolescence and into young adulthood, resulting in increased risks of mortality. Yet, very little is known about this group’s mortality risks later in life. The aim of this study was to investigate whether OHC was associated with the risk of all-cause mortality across adulthood, and whether these risks varied across different placement characteristics. Moreover, the study addressed potential confounding by including two comparison groups with children who grew up under similarly adverse living conditions but did not experience placement.Methods: Data were derived from a 60-year follow-up of a Stockholm cohort born in 1953 (n = 15 048), of whom around 9% have had experiences of OHC. The associations between OHC and subsequent all-cause mortality were analysed by means of Cox’s proportional hazards regression models.Results: Individuals who were placed in OHC at any point during their formative years had increased mortality risks across ages 20 to 56 years. Elevated risk of mortality was particularly pronounced among those who were placed in adolescence and/or because of their own behaviours. Children who were exposed to OHC had increased risks of mortality also when compared with those who grew up under similar living conditions but did not experience placement.Conclusions: Children in OHC constitute a high-risk group for subsequent mortality. In order to narrow the mortality gap, interventions may need to monitor not only health aspects but also to target the cognitive and social development of these children.
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| 10. |
- Gauffin, Karl, et al.
(author)
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School performance and alcohol-related disorders in early adulthood : a Swedish national cohort study
- 2015
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 44:3, s. 919-927
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Journal article (peer-reviewed)abstract
- Background Alcohol misuse is an important global health determinant and a major contributor to health inequalities. We aimed to investigate the association between school performance and alcohol-related disorders in early adulthood in a longitudinal register-based national cohort study. Methods We followed a register-based national cohort of Swedish citizens born 1973-1984 (N = 948 440) from compulsory school graduation at age 15-16 to 2009. We divided the population into five groups: high school marks (> mean+1 SD); high average (between mean and mean - 1 SD); low average (between mean and mean - 1 SD); low (< mean - 1SD); and missing. Cox proportional hazard models were used to investigate the relation between school marks at time of graduation and hospital care for alcohol-related disorders in early adulthood. Results There was a steep gradient in the risk of alcohol-related disorders related to school performance. In comparison with peers in the top category of school marks, students with low marks had adjusted hazard ratios of 8.02 [95% confidence interval (CI) 7.20 to 8.91], low average 3.02 (2.72 to 3.35) and high average 1.55 (1.39 to 1.73). The risk associated with low school marks was stronger in the male population and in the group from high socioeconomic background. Conclusions The study demonstrated a strong graded relation between low school performance and alcohol-related disorders in young adulthood. School performance should be taken into account when developing prevention programmes/policies targeting alcohol misuse among teenagers and young adults, especially if the aim is to reach high-risk groups.
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