| 1. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth order and mortality : a population-based cohort study
- 2015
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Ingår i: Demography. - : Duke University Press. - 0070-3370 .- 1533-7790. ; 52:2, s. 613-639
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Tidskriftsartikel (refereegranskat)abstract
- This study uses Swedish population register data to investigate the relationship between birth order and mortality in adulthood over the ages 30 to 69 for Swedish cohorts born between 1938 and 1960, using a within-family comparison. The main analyses are conducted with discrete-time survival analysis using a within-family comparison, and the estimates are adjusted for age, mother's age at the time of birth, and cohort. Focusing on sibships ranging in size from two to six, we find that mortality risk in adulthood increases with later birth order. The results show that the relative effect of birth order is greater amongst women than amongst men. This pattern is consistent for all the major causes of death, but is particularly pronounced for mortality attributable to cancers of the respiratory system, and external causes. Further analyses where we adjust for adult socioeconomic status and adult educational attainment suggest that social pathways only mediate the relationship between birth order and mortality risk in adulthood to a limited degree.
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| 2. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth spacing and health outcomes : differences across the life course and developmental contexts
- 2020
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Ingår i: Handbook on Demographic Change and the Lifecourse. - : Edward Elgar Publishing. - 9781788974868 - 9781788974875 ; , s. 170-181
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Bokkapitel (refereegranskat)abstract
- In this chapter the authors discuss research on the effects of long and short birth spacing from the perspective of children (the time interval between the births of adjacent siblings). Recent research has placed doubt on previous findings of adverse effects of short birth intervals on birth outcomes as well as short-, medium-, and long-term health, educational, and socioeconomic attainment outcomes. They summarize recent findings with a particular focus on impacts over the lifecourse, and the extent to which findings are applicable at various levels of social and economic development. The authors also briefly discuss the effects of birth spacing in the broader context of research examining the effects of early life conditions on adult outcomes.
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| 3. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth Spacing and Parents' Physical and Mental Health : An Analysis Using Individual and Sibling Fixed Effects
- 2024
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Ingår i: Demography. - 0070-3370 .- 1533-7790. ; 61:2, s. 393-418
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Tidskriftsartikel (refereegranskat)abstract
- An exten sive lit er a ture has exam ined the rela tion ship between birth spac ing and sub se quent health out comes for par ents, par tic u larly for moth ers. However, this research has drawn almost exclu sively on obser va tional research designs, and almost all stud ies have been lim ited to adjusting for observ able fac tors that could con found the rela tion ship between birth spac ing and health out comes. In this study, we use Nor we gian reg is ter data to exam ine the rela tion ship between birth spac ing and the num ber of gen eral prac ti tioner con sul ta tions for moth ers' and fathers' phys i cal and men tal health con cerns imme di ately after child birth (1-5 and 6-11 months after child birth), in the medium term (5-6 years after child bear ing), and in the long term (10-11 years after child bear ing). To exam ine short term health out comes, we esti mate indi vid ual fixed-effects mod els: we hold con stant fac tors that could influ ence par ents' birth spacing behav ior and their health, com par ing health out comes after differ ent births to the same par ent. We apply sib ling fixed effects in our anal y sis of medium- and long-term out comes, hold ing con stant moth ers' and fathers' fam ily back grounds. The results from our ana ly ses that do not apply indi vid ual or sib ling fixed effects are con sis tent with much of the pre vi ous lit er a ture: shorter and lon ger birth inter vals are asso ci ated with worse health out comes than birth inter vals of approx i ma tely 2-3 years. Estimates from indi vid ual fixed-effects mod els sug gest that par tic u larly short inter vals have a mod est neg a tive effect on mater nal men tal health in the short term, with more ambig u ous evi dence that par tic u larly short or long inter vals might mod estly influ ence short-, medium, and longterm phys i cal health out comes. Overall, these results are con sis tent with small to neg li gi ble effects of birth spac ing behav ior on (nonpreg nancyrelated) parental health outcomes.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- Baranowska-Rataj, Anna, 1980-, et al.
(författare)
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Preterm birth and educational disadvantage : heterogeneous effects
- 2023
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Ingår i: Population Studies. - : Routledge. - 0032-4728 .- 1477-4747. ; 77:3, s. 459-474
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Tidskriftsartikel (refereegranskat)abstract
- Although preterm birth is the leading cause of perinatal morbidity and mortality in advanced economies, evidence about the consequences of prematurity in later life is limited. Using Swedish registers for cohorts born 1982–94 (N = 1,087,750), we examine the effects of preterm birth on school grades at age 16 using sibling fixed effects models. We further examine how school grades are affected by degree of prematurity and the compensating roles of family socio-economic resources and characteristics of school districts. Our results show that the negative effects of preterm birth are observed mostly among children born extremely preterm (<28 weeks); children born moderately preterm (32–<37 weeks) suffer no ill effects. We do not find any evidence for a moderating effect of parental socio-economic resources. Children born extremely preterm and in the top decile of school districts achieve as good grades as children born at full term in an average school district.
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| 8. |
- Barclay, Kieron, 1986-
(författare)
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A within-family analysis of birth order and intelligence using population conscription data on Swedish men
- 2015
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Ingår i: Intelligence. - : Elsevier BV. - 0160-2896 .- 1873-7935. ; 49, s. 134-143
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the relationship between birth order and intelligence in Sweden. This research question has been of interest for decades, but only one study using a sibling comparison design has found that birth order has a negative effect on intelligence. The data used in this study is Swedish administrative register data, with data on cognitive ability drawn from the military conscription register for men born 1965 to 1977. Within-family comparison linear regression models are used to estimate the difference in cognitive ability by birth order amongst brothers. I find that there is a negative relationship between birth order and cognitive ability. This is consistent in sibling-group-size-specific analyses of sibling groups with two through to six children. Further analyses demonstrate that this negative relationship between birth order and intelligence is consistent in different socioeconomic status groups, and amongst individuals born in the 1960s and 1970s. Analyses of brothers in two-child sibling groups show that the relationship between birth order and intelligence varies by the birth interval. Second borns have a statistically significantly lower cognitive ability score if the birth interval is up to six years, but not if it is longer.
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| 9. |
- Barclay, Kieron, 1986-
(författare)
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Birth Order and Educational Attainment : evidence from Fully Adopted Sibling Groups
- 2015
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Ingår i: Intelligence. - : Elsevier BV. - 0160-2896 .- 1873-7935. ; 48, s. 109-122
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Tidskriftsartikel (refereegranskat)abstract
- This study uses data on fully adopted sibling groups to test whether the explanation for the consistently observed negative effects of birth order are physiological or social in origin. Swedish administrative register data is used to construct full sibling data for cohorts born 1960 to 1982. Using a within-family comparison approach, I compare adopted siblings of different adopted birth order to one another to see whether birth order amongst adopted children (N=6,968) is associated with educational attainment by age 30, and the likelihood of having entered tertiary education by age 30. These same within-family comparison analyses are also performed on siblings in fully biologically related sibling groups (N=1,588,401). I find that there is a negative relationship between adopted birth order and both educational attainment and the likelihood of entering tertiary education in fully adopted sibling sets. These findings strongly suggest that differences in educational attainment by birth order are driven by intrafamily social dynamics. I also conduct additional analyses in fully adopted sibling groups where age order and adoption order are reversed to test whether there is evidence for tutoring by siblings. These results do not indicate clear support for any tutoring effect.
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| 10. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth Order and Physical Fitness in Early Adulthood : Evidence from Swedish Military Conscription Data
- 2014
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Ingår i: Social Science and Medicine. - : Elsevier. - 0277-9536 .- 1873-5347. ; 123, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Physical fitness at young adult ages is an important determinant of physical health, cognitive ability, and mortality. However, few studies have addressed the relationship between early life conditions and physical fitness in adulthood. An important potential factor influencing physical fitness is birth order, which prior studies associate with several early- and later-life outcomes such as height and mortality. This is the first study to analyse the association between birth order and physical fitness in late adolescence. We use military conscription data on 218,873 Swedish males born between 1965 and 1977. Physical fitness is measured by a test of maximal working capacity, a measure of cardiovascular fitness closely related to V02max. We use linear regression with sibling fixed effects, meaning a within-family comparison, to eliminate the confounding influence of unobserved factors that vary between siblings. To understand the mechanism we further analyse whether the association between birth order and physical fitness varies by sibship size, parental socioeconomic status, birth cohort or length of the birth interval. We find a strong, negative and monotonic relationship between birth order and physical fitness. For example, third-born children have a maximal working capacity approximately 0.1 (p<0.000) standard deviations lower than first-born children. The association exists both in small (3 or less children) and large families (4 or more children), in high and low socioeconomic status families, and amongst cohorts born in the 1960s and the 1970s. While in the whole population the birth order effect does not depend on the length of the birth intervals, in two-child families a longer birth interval strengthens the advantage of the first-born. Our results illustrate the importance of birth order on physical fitness, and suggest that the first-born advantage already arises in late adolescence.
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