Sex ratios at sexual maturity and longevity: evidence from Swedish register data

Background: This study tests the recently proposed hypothesis that the contextual sex ratio at sexual maturity is related to longevity. Previous empirical research in the United States has shown that a higher proportion of males at the age of sexual maturity increases the risk of mortality for males both before and after the age of 65. Methods: I use Swedish administrative register data, linking the 1960 census to individual-level mortality data over the period 1960 to 2007. I calculate the sex ratio at two geographic levels, municipalities and parishes. Two different specifications of the sex ratio are calculated: males aged 18 to 27 over females aged 15 to 24, and males aged 18 to 22 over females aged 16 to 20. I conduct piece-wise constant survival analyses over the period from 1960 to 2007 to analyze the risk of mortality before age 65. I run separate analyses for males and females, using cohorts born in 1941 and 1942. Results: For males, the results generally show that for both males and females a higher proportion of males was associated with a lower relative risk of mortality before age 65. The results were not statistically significant. Conclusions: The lack of a consistent statistically significant association for either males or females, and the trend for males being in the opposite direction of what was hypothesized, suggests that support for the hypothesis in Sweden is very weak

The birth order paradox: sibling differences in educational attainment

This study uses population register data to examine the relationship between birth order and educational attainment in Sweden, and demonstrates that while the net effect of birth order on educational attainment is negative, later-born children often spend longer in education. The explanation for this finding is due to educational expansion in Sweden in the 20th century, which outweighs the negative causal effect of birth order for the affected cohorts. This is particularly true for women due to the fact that the rate of increasing educational enrolment has been greater for women than for men. These results also show that later-borns in large families particularly benefit from educational expansion due to the longer average birth interval between the first and last child in large families, meaning that the supply of educational opportunities increased to a greater extent in the intervening period. However, in periods where education is not expanding, later-born siblings continue to fare worse than first-borns

Maternal age and offspring health and health behaviours in late adolescence in Sweden

In this study we investigate the relationship between maternal age at the time of birth and a variety of health behaviours and measures of health amongst young adults in contemporary Sweden. Previous research has shown that those born to younger and older mothers tend to have worse perinatal outcomes, and worse health in middle- and later adulthood. However, previous work has not examined health in early adulthood, and no studies have explored whether maternal age is related to health behaviours. Using survey data on 1,236 19-year olds born in Sweden in 1990, we find that those born to older mothers have lower self-rated health, are more likely to smoke, more likely to drink alcohol regularly, and less likely to exercise regularly. We discuss potential explanations for these findings, such as older parents exerting lower social control due to greater levels of workplace responsibilities and time demands, long-term consequences of the poor peri-natal outcomes of those born to older mothers, as well as the potential role of parental health behaviours. Our findings suggest that health behaviours may play an important mediating role in explaining the worse long-term health of those born to younger and older mothers

Maternal age and offspring health and health behaviours in late adolescence in Sweden

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The long-term cognitive and socioeconomic consequences of birth intervals: a within-family sibling comparison using Swedish register data

We examine the relationship between birth-to-birth intervals and a variety of midand long-term cognitive and socioeconomic outcomes, including high school GPA, cognitive ability, educational attainment, earnings, unemployment status, and receiving government welfare support. Using contemporary Swedish population register data and a within-family sibling comparison design, we find that neither the birth interval preceding the index person, nor the birth interval following the index person, are associated with any substantively meaningful changes in mid- or long-term outcomes. This is true even for individuals born before or after birth-to-birth intervals of less than 12 months. We conclude that in a contemporary high income welfare state there appear to be no relationship between unusually short or long birth intervals and adverse long-term outcomes

Peer clustering of exercise and eating behaviours among young adults in Sweden: a cross-sectional study of egocentric network data

Background Research suggests that the growing prevalence of obesity may be related to the influence of the health behaviours of peers. We look at clustering of exercise and eating behaviours amongst a previously unstudied group, young adults in Sweden. Previous research has mainly been conducted in the United States and Britain, countries that have relatively high rates of obesity. Methods Using ego-alter dyads from the egocentric network data as the unit of analysis, we conduct logistic regressions to investigate the association between ego and alter exercise and eating behaviours. Results Respondents have a significantly greater probability of engaging in regular exercise and eating healthily if a nominated peer also does so. Furthermore, the degree to which this behavior is shared is modulated by the strength of the relationship between the two individuals, with a greater probability of engaging in these behaviours observed when the relationship with the nominated peer is strong relative to when the relationship is weak. However, we find that ego-alter homogeneity in terms of gender and migration status was not associated with a significantly greater probability of behaving in a similar manner to a nominated peer. Furthermore, the status of the nominated peer as a relative or not did not impact the probability that the ego would engage in similar health behaviours to that alter. Conclusions We observe strong associations between ego and alter health behaviours for young adults, consistent with previous research. Although we cannot draw causal inferences, these results suggest that the health behaviours of an individual’s peers may play a role in shaping their own health behaviours

When and Where Birth Spacing Matters for Child Survival: An International Comparison Using the DHS: an international comparison using the DHS

A large body of research has found an association between short birth intervals and the risk of infant mortality in developing countries, but recent work on other perinatal outcomes from highly developed countries has called these claims into question, arguing that previous studies have failed to adequately control for unobserved heterogeneity. Our study addresses this issue by estimating within-family models on a sample of 4.5 million births from 77 countries at various levels of development. We show that after unobserved maternal heterogeneity is controlled for, intervals shorter than 36 months substantially increase the probability of infant death. However, the importance of birth intervals as a determinant of infant mortality varies inversely with maternal education and the strength of the relationship varies regionally. Finally, we demonstrate that the mortality-reducing effects of longer birth intervals are strong at low levels of development but decline steadily toward zero at higher levels of development. These findings offer a clear way to reconcile previous research showing that birth intervals are important for perinatal outcomes in low-income countries but are much less consequential in high-income settings

Health outcomes of only children across the life course : an investigation using Swedish register data

This work was partially supported by the Carnegie Trust for the Universities of Scotland [RIG008234] awarded to Katherine Keenan and by the Economic and Social Research Council [grant number ES/S002103/1] to Alice Goisis. This work was also supported by the Swedish Research Council (Vetenskapsrådet) via the Swedish Initiative for Research on Microdata in the Social and Medical Sciences (SIMSAM), grant 340-2013-5164.Only children (with no full biological siblings) are a growing subgroup in many high-income settings. Previous studies have largely focused on the short-term developmental outcomes of only children, but there is limited evidence on their health outcomes. Using Swedish population register data for cohorts born 1940–75, we compare the health of only children with that of children from multi-child sibling groups, taking into account birth order, family size, and presence of half-siblings. Only children showed lower height and fitness scores, were more likely to be overweight/obese in late adolescence, and experienced higher later-life mortality than those with one or two siblings. However, only children without half-siblings were consistently healthier than those with half-siblings, suggesting that parental disruption confers additional disadvantages. The health disadvantage was attenuated but not fully explained by adjustment for parental characteristics and after using within-family maternal cousin comparison designs.Publisher PDFPeer reviewe

Advantages of later motherhood

Peer reviewe

Health outcomes of only children across the life course : an investigation using Swedish register data

The proportion of only children – children with no full biological siblings – is growing in high-income settings, but we know little about their life course outcomes and how this is related to long-term health. Previous studies of only children have tended to focus on short-term, developmental and intellectual outcomes in early life or adolescence, and provide mixed evidence. Using Swedish population register data on children born between 1940 and 1975, we compare only children with children from multi-child sibling groups, taking into account birth order, family size and half-siblings to account for family complexity. We consider physical health outcomes measured at late adolescence (height, body mass index and physical fitness), and mortality. Only children with and without half-siblings had lower height and fitness scores, were more likely to be overweight or obese, and had higher mortality, than those with 1 or 2 biological siblings. Only children without half-siblings generally did better than only children with half-siblings, suggesting that only children experiencing parental disruption experience additional disadvantages. With the exception of height, the patterns persist after adjustment for parental characteristics and after employing within-family cousin comparison designs. In mortality models, some of the excess risk for only children was explained by adjustment for fertility, marriage and educational history. We discuss the extent to which the patterns we observe are explained by selection processes and contextual differences in the prevalence of one-child sibling groups.Publisher PD