| 1. |
- Gardner, Eugene J., et al.
(författare)
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Reduced reproductive success is associated with selective constraint on human genes
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 603:7903, s. 858-863
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide sequencing of human populations has revealed substantial variation among genes in the intensity of purifying selection acting on damaging genetic variants1. Although genes under the strongest selective constraint are highly enriched for associations with Mendelian disorders, most of these genes are not associated with disease and therefore the nature of the selection acting on them is not known2. Here we show that genetic variants that damage these genes are associated with markedly reduced reproductive success, primarily owing to increased childlessness, with a stronger effect in males than in females. We present evidence that increased childlessness is probably mediated by genetically associated cognitive and behavioural traits, which may mean that male carriers are less likely to find reproductive partners. This reduction in reproductive success may account for 20% of purifying selection against heterozygous variants that ablate protein-coding genes. Although this genetic association may only account for a very minor fraction of the overall likelihood of being childless (less than 1%), especially when compared to more influential sociodemographic factors, it may influence how genes evolve over time.
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| 2. |
- Aradhya, Siddartha, et al.
(författare)
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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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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 52:1, s. 156-164
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Baier, Tina, et al.
(författare)
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Genetic Influences on Educational Achievement in Cross-National Perspective
- 2022
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Ingår i: European Sociological Review. - : Oxford University Press (OUP). - 0266-7215 .- 1468-2672. ; 38:6, s. 959-974
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing interest in how social conditions moderate genetic influences on education [gene–environment interactions (GxE)]. Previous research has focused on the family, specifically parents’ social background, and has neglected the institutional environment. To assess the impact of macro-level influences, we compare genetic influences on educational achievement and their social stratification across Germany, Norway, Sweden, and the United States. We combine well-established GxE-conceptualizations with the comparative stratification literature and propose that educational systems and welfare-state regimes affect the realization of genetic potential. We analyse population-representative survey data on twins (Germany and the United States) and twin registers (Norway and Sweden), and estimate genetically sensitive variance decomposition models. Our comparative design yields three main findings. First, Germany stands out with comparatively weak genetic influences on educational achievement suggesting that early tracking limits the realization thereof. Second, in the United States genetic influences are comparatively strong and similar in size compared to the Nordic countries. Third, in Sweden genetic influences are stronger among disadvantaged families supporting the expectation that challenging and uncertain circumstances promote genetic expression. This ideosyncratic finding must be related to features of Swedish social institutions or welfare-state arrangements that are not found in otherwise similar countries.
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| 4. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth Spacing and Health and Socioeconomic Outcomes Across the Life Course : Evidence From the Utah Population Database
- 2022
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Ingår i: Demography. - : Duke University Press. - 0070-3370 .- 1533-7790. ; 59:3, s. 1117-1142
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between birth interval length and child outcomes has received increased attention in recent years, but few studies have examined offspring outcomes across the life course in North America. We use data from the Utah Population Database to examine the relationship between birth intervals and short- and long-term outcomes: preterm birth, low birth weight (LBW), infant mortality, college degree attainment, occupational status, and adult mortality. Using linear regression, linear probability models, and survival analysis, we compare results from models with and without sibling comparisons. Children born after a birth interval of 9–12 months have a higher probability of LBW, preterm birth, and infant mortality both with and without sibling comparisons; longer intervals are associated with a lower probability of these outcomes. Short intervals before the birth of the next youngest sibling are also associated with LBW, preterm birth, and infant mortality both with and without sibling comparisons. This pattern raises concerns that the sibling comparison models do not fully adjust for within-family factors predicting both spacing and perinatal outcomes. In sibling comparison analyses considering long-term outcomes, not even the very shortest birth intervals are negatively associated with educational or occupational outcomes or with long-term mortality. These findings suggest that extremely short birth intervals may increase the probability of poor perinatal outcomes but that any such disadvantages disappear over the extended life course.
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| 5. |
- Bishop, Lauren, et al.
(författare)
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Birth order and health events attributable to alcohol and narcotics in midlife : A 25-year follow-up of a national Swedish birth cohort and their siblings
- 2022
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Ingår i: SSM - Population Health. - : Elsevier BV. - 2352-8273. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Higher birth order is associated with increased risks of adverse health outcomes attributable to alcohol or narcotics in adolescence, but it remains unclear whether these observed birth order effects are also present in midlife. Drawing on a national Swedish cohort born in 1953 and their siblings, we estimate associations between birth order and alcohol- or narcotics-attributable hospitalization or death with a 25-year follow-up to assess whether birth order differences are observed during this life course period. Health events attributable to alcohol or narcotics use were identified using the Swedish National Patient and Cause of Death registers, respectively. Weapply Cox proportional hazards models to estimate average birth order differences in hazards for alcohol- or narcotics-attributable hospitalization or death between ages 30 and 55. We estimate birth order differences between families, and use two fixed-effects approaches to estimate birth order differences within families and within families of the same type. Bivariate results indicate increased hazards for both outcomes with higher birthorder; however, these results are no longer observed after adjustment for familial background characteristics in all models. Our results thereby show limited evidence for birth order differences in midlife. This study highlights that shared factors within the family of origin may be stronger predictors of adverse health outcomes attributable to substance use among siblings during this life course period. Future research should disentangle the contributions of the social environment within the family of origin for adverse health outcomes attributable to alcohol or narcotics among siblings.
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| 6. |
- Bishop, Lauren, 1987-
(författare)
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Under the influence : Substance misuse from the perspective of linked lives
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Health risk behaviors shape, and are shaped by, the people with whom we interact throughout our lives. The use of substances, including alcohol or narcotics, is one such behavior, yet it is often empirically examined in isolation of other people. As such, it has been repeatedly shown that excessive alcohol consumption, illicit drug use, and the extra-medical use of prescription narcotics are, collectively, a leading cause of preventable injury, severe illness, and premature death. However, by not considering that substance use which leads to harms (hereafter, substance misuse) is inseparable from social contexts, the burden of substance misuse may be greatly underestimated. Drawing on a Swedish birth cohort from 1953, and centered on the concept of interdependent—linked—lives, this thesis encompasses four empirical studies of social relationships and substance misuse. Each study examines the association between substance misuse and friends and parents, siblings, spouses, and offspring, respectively. Study I explored whether childhood adversity in two contexts, within the family of origin and among one’s adolescent friends at age 13, was a potential risk factor for later substance misuse. The study found independent associations between substance misuse and childhood adversity in both contexts. Study II estimated differences in substance misuse between siblings in midlife according to birth order, and showed that substance misuse during this life course period may be better explained by factors within the family of origin. Study III examined the effects of substance misuse on nearly 50 years of marital status transitions. The results suggest that a lifetime history of substance misuse affects marital status transitions, and that substance misuse may increase the risk of marital dissolution. Finally, in investigating changes in parental psychotropic medication use in relation to their offspring’s hospitalization for substance misuse, Study IV demonstrated that such stressful life events as an offspring’s hospitalization for narcotics use may have a detrimental impact on maternal mental health. The findings from the thesis underscore that factors within the families of both origin and destination have the potential to affect, and be affected by, substance misuse throughout the life course. The thesis concludes substance misuse neither starts, nor ends, with the individual. Accordingly, public health efforts could benefit from approaching substance misuse from the perspective of linked lives.
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| 7. |
- Chanfreau, Jenny, et al.
(författare)
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Sibling group size and BMI over the life course : Evidence from four British cohort studies
- 2022
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Ingår i: Advances in Life Course Research. - : Elsevier BV. - 1040-2608. ; 53
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Tidskriftsartikel (refereegranskat)abstract
- Only children, here defined as individuals growing up without siblings, are a small but growing demographic subgroup. Existing research has consistently shown that, on average, only children have higher body mass index (BMI) than individuals who grow up with siblings. How this difference develops with age is unclear and existing evidence is inconclusive regarding the underlying mechanisms. We investigate BMI trajectories for only children and those with siblings up to late adolescence for four British birth cohorts and across adulthood for three cohorts. We use data on BMI from ages 2–63 years (cohort born 1946); 7–55 years (born 1958); 10–46 (born 1970) and 3–17 years (born 2000–2002). Using mixed effects regression separately for each cohort, we estimate the change in BMI by age comparing only children and those with siblings. The results show higher average BMI among only children in each cohort, yet the difference is substantively small and limited to school age and adolescence. The association between sibling status and BMI at age 10/11 is not explained by differential health behaviours (physical activity, inactivity and diet) or individual or family background characteristics in any of the cohorts. Although persistent across cohorts, and despite the underlying mechanism remaining unexplained, the substantively small magnitude of the observed difference and the convergence of the trajectories by early adulthood in all cohorts raises doubts about whether the difference in BMI between only children and siblings in the UK context should be of research or clinical concern. Future research could usefully be directed more at whether only children experience elevated rates of disease, for which high BMI is a risk factor, at different stages of the life course and across contexts.
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