Socio-economic differences in body mass index: the contribution of genetic factors.

BACKGROUND: Higher mean body mass index (BMI) among lower socioeconomic position (SEP) groups is well established in Western societies, but the influence of genetic factors on these differences is not well characterized. METHODS: We analyzed these associations using Finnish health surveys conducted between 1992 and 2017 (N = 33 523; 53% women) with information on measured weight and height, polygenic risk scores of BMI (PGS-BMI) and linked data from administrative registers to measure educational attainment, occupation-based social class and personal income. RESULTS: In linear regressions, largest adjusted BMI differences were found between basic and tertiary educated men (1.4 kg/m2, 95% confidence interval [CI] 1.2; 1.6) and women (2.5 kg/m2, 95% CI 2.3; 2.8), and inverse BMI gradients were also found for social class and income. These SEP differences arose partly because mean PGS-BMI was higher and partly because PGS-BMI predicted BMI more strongly in lower SEP groups. The inverse SEP gradients of BMI were steeper in women than in men, but sex differences were not found in the genetic contributions to these differences. CONCLUSIONS: Better understanding of the interplay between genes and environment provides insight into the mechanisms explaining SEP differences in BMI.

Does having siblings really protect against childhood atopic diseases? A total population and within-family analysis.

The association between having older siblings and decreased risk for atopic symptoms is well-established. This has been interpreted as evidence for the microbiota hypothesis, i.e. that increased early-childhood microbial exposure caused by siblings protects from immune hypersensitivities. However, possible confounders of the association have received little attention. We used register data on Finnish cohorts born in 1995-2004 (N = 559,077) to assess medication purchases for atopic diseases: antihistamines, eczema medication, asthma medication and Epinephrine. We modelled the probability of atopic medication purchases at ages 0-15 by birth order controlling for important observed confounders and all unobserved genetic and environmental characteristics shared by siblings in a within-family fixed effects model. We further studied medication purchases among first-borns according to the age difference with younger siblings to assess whether having younger siblings in early childhood is beneficial. Having older siblings was associated with a lower probability of atopic medication purchases. Compared to first-borns, the probability was 10-20% lower among second-borns, 20-40% lower among third-borns, and 30-70% lower among subsequent children, depending on medication type. Confounding accounted for up to 75% of these differences, particularly for asthma and eczema medication, but significant differences by birth order remained across all medication types. Among first-borns, a smaller age difference with younger siblings was related to a lower likelihood of atopic medication use. Our results, based on designs that account for unobserved confounding, show that exposure to siblings in early childhood, protects from atopic diseases, and thus strongly support the microbiota hypothesis.

One generation apart: Individual income and life expectancy in two Swedish cohorts born before and after the expansion of the welfare state.

AIMS: Social inequalities in mortality persist or even increase in high-income countries. Most evidence is based on a period approach to measuring mortality - that is, data from individuals born decades apart. A cohort approach, however, provides complementary insights using data from individuals who grow up and age under similar social and institutional arrangements. This study compares income inequalities in cohort life expectancy in two Swedish cohorts, one born before and one born after the expansion of the welfare state. METHODS: Data on individuals born in Sweden in 1922-1926 and 1951-1955 were obtained from total population registries. These data were linked to individual disposable income from 1970 and 1999 and mortality between 50 and 61 years of age in 1972-1987 and 2001-2016, respectively. We calculated cohort temporary life expectancies in the two cohorts by income and gender. RESULTS: Life expectancy, income, and income inequalities in life expectancy increased between the two cohorts, for both men and women. Women born in 1922-1926 had modest income differences in life expectancy, but pronounced differences emerged in the cohort born in 1951-1955. Men with low incomes born in 1951-1955 had roughly similar life expectancy as those with low incomes born in 1922-1926. CONCLUSIONS: Compared with a period approach to life expectancy trends, the cohort approach highlights the stagnation of mortality at the lowest income groups for men and the rapid emergence of a mortality gradient for women. Future research on health inequalities in welfare states should consider underlying factors both from a cohort and period perspective.

Changes in Chlamydia trachomatis risk before and after union formation and separation among women of reproductive age.

BACKGROUND: Not having an established relationship is associated with an elevated risk of Chlamydia trachomatis (CT) infection, but this might reflect selection into and out of unions. Although union formation and union separation are common events in reproductive age, little is known about changes in CT risk before and after these transitions. METHODS: We linked Finnish Population Register data to the National Register of Infectious Diseases and used fixed-effects linear probability models that account for all time-invariant confounders to examine changes in women's 6-month CT risk 3 years before and 3 years after entry into first cohabitation (n = 293 554), non-marital separation (n = 201 647) or marital separation (n = 92 232) during 2005-14. RESULTS: From 3 years to 1 year before first union formation, the 6-month risk of CT increased slightly, peaking at 1.27% immediately prior to union formation (95% confidence interval 1.22-1.31). It declined sharply following union formation, being only 0.40% (0.34-0.46) 6-12 months after union formation with little changes thereafter. Among women separating from non-marital unions, the risk increased from 0.50% (0.42-0.57) to 1.45% (1.40-1.49) around the time of separation and decreased following separation. The pattern of findings was relatively similar for marital separation, although the observed risks and changes were smaller in magnitude. CONCLUSIONS: Our results based on longitudinal data and individual fixed-effects models indicate that the period immediately after separation may be causally associated with an elevated risk of CT. This suggests that recently separated women should be identified as a high-risk group for CT.

Fatherhood timing and men's midlife earnings: A within-family study of Finnish cohorts born in 1938-50.

Fathers tend to achieve higher earnings than childless men, but there is limited evidence on the associations between fatherhood timing and men's later earnings. Using a longitudinal census-based sample of Finnish men, including a subsample of brothers, we investigated fatherhood timing and men's midlife earnings using both between- and within-family models. Earnings around age 50 were lower among adolescent and young fathers than for men who became fathers at ages 25-29 or later, but these associations became negligible after accounting for measured confounders and unobserved familial confounding. Overall, our findings highlight the important roles of selection into early childbearing and into childlessness. At the population level, early fatherhood was associated with clear negative distributional shifts in fathers' midlife earnings. However, among all men, any influence of fatherhood timing on men's midlife earnings distribution paled in comparison with that of childlessness.

Grandparental support and maternal depression: Do grandparents' characteristics matter more for separating mothers?

Grandparental support may protect mothers from depression, particularly mothers who separate and enter single parenthood. Using longitudinal Finnish register data on 116,917 separating and 371,703 non-separating mothers with young children, we examined differences in mothers' antidepressant purchases by grandparental characteristics related to provision of support. Grandparents' younger age (<70 years), employment, and lack of severe health problems predicted a lower probability of maternal depression. Depression was also less common if grandparents lived close to the mother and if the maternal grandparents' union was intact. Differences in maternal depression by grandparental characteristics were larger among separating than among non-separating mothers, particularly during the years before separation. Overall, maternal grandmothers' characteristics appeared to matter most, while the role of paternal grandparents was smaller. The findings suggest that grandparental characteristics associated with increased potential for providing support and decreased need of receiving support predict a lower likelihood of maternal depression, particularly among separating mothers.

Medically assisted reproduction and mental health: a 24-year longitudinal analysis using Finnish register data.

BACKGROUND: Medically assisted reproduction can negatively affect women's mental health, particularly when the treatments do not result in a live birth. Although the number of women relying on medically assisted reproduction to conceive has grown rapidly, our knowledge about the mental health effects before, during, and after treatment is limited. OBJECTIVE: This study aimed to understand the long-term association between medically assisted reproduction and mental health outcomes for women before, during, and after their treatments, and according to whether the treatment resulted in a live birth. STUDY DESIGN: Using Finnish register data for the period from 1995 to 2018, we estimated the probability of psychotropic purchases (antidepressants, anxiolytics, hypnotics, and sedatives) for 3 groups of women who: (1) gave birth after natural conception, (2) gave birth after medically assisted reproduction treatments, or (3) underwent medically assisted reproduction but remained childless. We followed up women for up to 12 years before and 12 years after the reference date, which corresponded to the conception date for women who had a first live birth either after a natural or a medically assisted conception, or the date of the last medically assisted reproduction treatment for women with no live birth by the end of 2017. We estimated linear probability models before and after adjustment for sociodemographic characteristics. RESULTS: The results show that women who did not have a live birth after undergoing medically assisted reproduction treatments purchased more psychotropics than women who gave birth after conceiving naturally or through medically assisted reproduction, and that these differences did not attenuate over time. Twelve years after the reference date, 17.73% (95% confidence interval, 16.82-18.63) of women who underwent medically assisted reproduction but remained childless purchased psychotropics vs 11.11% of women who gave birth after natural conception (95% confidence interval, 10.98-11.26) and 12.17% (95% confidence interval, 11.65-12.69) of women who gave birth after medically assisted reproduction treatments. In addition, women who conceived naturally and through medically assisted reproduction had very similar psychotropic use patterns from 3 years before conception to 4 years after, and over the long term. Adjustment for women's sociodemographic characteristics did not change the results. CONCLUSION: The similarities in psychotropic purchases of women who had a live birth, whether naturally or through medically assisted reproduction, suggest that the higher psychotropic use among women who remained childless after undergoing medically assisted reproduction were likely driven more by involuntary childlessness than by treatment-related stress. The results highlight the importance of counseling for women undergoing medically assisted reproduction treatments, especially if their attempts to conceive are unsuccessful.

Labor epidural analgesia and subsequent risk of offspring autism spectrum disorder and attention-deficit/hyperactivity disorder: a cross-national cohort study of 4.5 million individuals and their siblings.

BACKGROUND: A recent study has suggested that labor epidural analgesia may be associated with increased rates of offspring autism spectrum disorder. Subsequent replication attempts have lacked sufficient power to confidently exclude the possibility of a small effect, and the causal nature of this association remains unknown. OBJECTIVE: This study aimed to investigate the extent to which exposure to labor epidural analgesia is associated with offspring autism spectrum disorder and attention-deficit/hyperactivity disorder following adjustments for unmeasured familial confounding. STUDY DESIGN: We identified 4,498,462 singletons and their parents using the Medical Birth Registers in Finland (cohorts born from 1987-2005), Norway (1999-2015), and Sweden (1987-2011) linked with population and patient registries. These cohorts were followed from birth until they either had the outcomes of interest, emigrated, died, or reached the end of the follow-up (at mean ages 13.6-16.8 years), whichever occurred first. Cox regression models were used to estimate country-specific associations between labor epidural analgesia recorded at birth and outcomes (eg, at least 1 secondary care diagnosis of autism spectrum disorder and attention-deficit/hyperactivity disorder or at least 1 dispensed prescription of medication used for the treatment of attention-deficit/hyperactivity disorder). The models were adjusted for sex, birth year, birth order, and unmeasured familial confounders via sibling comparisons. Pooled estimates across all the 3 countries were estimated using inverse variance weighted fixed-effects meta-analysis models. RESULTS: A total of 4,498,462 individuals (48.7% female) were included, 1,091,846 (24.3%) of which were exposed to labor epidural analgesia. Of these, 1.2% were diagnosed with autism spectrum disorder and 4.0% with attention-deficit/hyperactivity disorder. On the population level, pooled estimates showed that labor epidural analgesia was associated with increased risk of offspring autism spectrum disorder (adjusted hazard ratio, 1.12; 95% confidence interval, 1.10-1.14, absolute risks, 1.20% vs 1.07%) and attention-deficit/hyperactivity disorder (adjusted hazard ratio, 1.20; 95% confidence interval, 1.19-1.21; absolute risks, 3.95% vs 3.32%). However, when comparing full siblings who were differentially exposed to labor epidural analgesia, the associations were fully attenuated for both conditions with narrow confidence intervals (adjusted hazard ratio [autism spectrum disorder], 0.98; 95% confidence interval, 0.93-1.03; adjusted hazard ratio attention-deficit/hyperactivity disorder, 0.99; 95% confidence interval, 0.96-1.02). CONCLUSION: In this large cross-national study, we found no support for the hypothesis that exposure to labor epidural analgesia causes either offspring autism spectrum disorder or attention-deficit/hyperactivity disorder.

Birth size, school performance and family social position: a study of 650,000 children.

BACKGROUND: Low birth weight (BW) is associated with lower cognitive functioning, but less is known of these associations across the full range of the BW distribution and its components. We analyzed how BW, birth length (BL) and birth ponderal index (BPI, kg/m3) are associated with school performance and how childhood family social position modifies these associations. METHODS: Medical birth records of all Finnish children born in 1987-1997 were linked to school performance records at 16 years of age (N = 642,425). We used population averaged and within-siblings fixed-effects linear regression models. RESULTS: BL showed a linear and BW a curvilinear association with school performance whereas for BPI the association was weak. The strongest association was found for BL explaining 0.08% of the variation in school performance in boys and 0.14% in girls. Demographic, gestational and social factors partly explained these associations. Similar but weaker associations were found within sibships. The association of BL with school performance was stronger at lower levels of family social position. CONCLUSION: BL shows a linear association with school performance and can explain more school performance variation than BW. At the population level, BL can offer useful information on intrauterine environmental factors relevant for cognitive performance. IMPACT: Birth length is linearly associated with school performance in late adolescence and explains a larger proportion of school performance variation than birth weight. The association between birth length and school performance is stronger in families with lower socio-economic position. At the population level, birth length can offer information on the intrauterine environment relevant for later cognitive performance.

Polygenic Prediction of Education and Its Role in the Intergenerational Transmission of Education: Cohort Changes Among Finnish Men and Women Born in 1925-1989.

Major changes in the educational distribution of the population and in institutions over the past century have affected the societal barriers to educational attainment. These changes can possibly result in stronger genetic associations. Using genetically informed, population-representative Finnish surveys linked to administrative registers, we investigated the polygenic associations and intergenerational transmission of education for those born between 1925 and 1989. First, we found that a polygenic index (PGI) designed to capture genetic predisposition to education strongly increased the predictiveness of educational attainment in pre-1950s cohorts, particularly among women. When decomposing the total contribution of PGI across different educational transitions, the transition between the basic and academic secondary tracks was the most important. This transition accounted for 60-80% of the total PGI-education association among most cohorts. The transition between academic secondary and higher tertiary levels increased its contribution across cohorts. Second, for cohorts born between 1955 and 1984, we observed that one eighth of the association between parental and one's own education is explained by the PGI. There was also an increase in the intergenerational correlation of education among these cohorts, which was partly explained by an increasing association between family education of origin and the PGI.

Does the suddenness matter? Antidepressant use before and after a spouse dies suddenly or expectedly of stroke.

Aims: Changes in mental health at the time of widowhood may depend on the expectedness of spousal death, but scant evidence is available for spousal deaths attributable to stroke. Methods: Using register-linkage data for Finland, we assessed changes in antidepressant use before and after spousal death for those whose spouses died suddenly of stroke between 1998 and 2003 (N=1820) and for those whose spouses died expectedly of stroke, with prior hospitalisation for cerebrovascular disease (N=1636). We used both population-averaged logit models and individual fixed-effects linear probability models. The latter models control for unobserved time-invariant heterogeneity between the individuals. Results: Our study indicates that the suddenness of a spouse's death from stroke plays a role in the well-being of the surviving spouse. Increases in antidepressant use appeared larger following widowhood for those whose spouses died suddenly of stroke relative to those whose spouses had a medical history of cerebrovascular disease. Conclusions: The suddenness of a spouse's death from stroke plays a role for the surviving spouse. The results suggest multifaceted timings of distress surrounding spousal death, depending on the suddenness of a spouse's death from stroke.

Socioeconomic differences in children's victimization to maternal and paternal violence: a register-based study.

AIMS: To explore the potential of administrative data in assessment of the association between parental socioeconomic position (SEP) and children's violent victimization by biological parents. METHODS: A longitudinal register-linkage study based on child-mother and child-father data, including all children born in Finland between 1991 and 2017. The data included 1,535,428 children, 796,335 biological mothers, and 775,966 fathers. We used logistic regression with person-years as observations and cluster-robust standard errors to predict children's violent victimization in 2009-2018 and assessed effect modification by child's age and gender. RESULTS: For the SEP indicators, lower maternal education (adjusted odds ratio (OR) 2.90, secondary education OR 1.99) and lower paternal education (OR 2.24, secondary education OR 1.59) were risk factors for violent victimization. Parental social assistance receipt (OR 2.4) and non-employment (OR 1.8-1.9) increased the risk of victimization to maternal and paternal violence. Income was associated with victimization in a gradient-like manner, with ORs ranging from 1.14 to 1.98 among mothers and from 1.29 to 2.56 among fathers. Children with low parental SEP were at the highest risk of parental violence, particularly paternal violence, at ages 3-8 years. CONCLUSIONS: All indicators of low SEP increased the risk of children experiencing both maternal and paternal physical violence, especially at ages 3-8 years. Longitudinal register data-because of large samples, no nonresponse or self-report bias, and the possibility to analyze violence committed by mother and father and age-groups separately-have great potential for comprehensive research on the risk factors of parental violence that are difficult to reliably assess with other types of data.

Adjustment for survey non-participation using record linkage and multiple imputation: A validity assessment exercise using the Health 2000 survey.

AIMS: It is becoming increasingly possible to obtain additional information about health survey participants, though not usually non-participants, via record linkage. We aimed to assess the validity of an assumption underpinning a method developed to mitigate non-participation bias. We use a survey in Finland where it is possible to link both participants and non-participants to administrative registers. Survey-derived alcohol consumption is used as the exemplar outcome. METHODS: Data on participants (85.5%) and true non-participants of the Finnish Health 2000 survey (invited survey sample N=7167 aged 30-79 years) and a contemporaneous register-based population sample (N=496,079) were individually linked to alcohol-related hospitalisation and death records. Applying the methodology to create synthetic observations on non-participants, we created 'inferred samples' (participants and inferred non-participants). Relative differences (RDs) between the inferred sample and the invited survey sample were estimated overall and by education. Five per cent limits were used to define acceptable RDs. RESULTS: Average weekly consumption estimates for men were 129 g and 131 g of alcohol in inferred and invited survey samples, respectively (RD -1.6%; 95% confidence interval (CI) -2.2 to -0.04%) and 35 g for women in both samples (RD -1.1%; 95% CI -2.4 to -0.8%). Estimates for men with secondary levels of education had the greatest RD (-2.4%; 95% CI -3.7 to -1.1%). CONCLUSIONS: The sufficiently small RDs between inferred and invited survey samples support the assumption validity and use of our methodology for adjusting for non-participation. However, the presence of some significant differences means caution is required.

Sociodemographic inequalities in mortality from drowning in the Baltic countries and Finland in 2000-2015: a register-based study.

BACKGROUND: Drowning is an important public health problem. Some evidence suggests that the risk of drowning is not distributed evenly across the general population. However, there has been comparatively little research on inequalities in drowning mortality. To address this deficit, this study examined trends and sociodemographic inequalities in mortality from unintentional drowning in the Baltic countries and Finland in 2000-2015. METHODS: Data for Estonia, Latvia and Lithuania came from longitudinal mortality follow-up studies of population censuses in 2000/2001 and 2011, while corresponding data for Finland were obtained from the longitudinal register-based population data file of Statistics Finland. Deaths from drowning (ICD-10 codes W65-W74) were obtained from national mortality registries. Information was also obtained on socioeconomic status (educational level) and urban-rural residence. Age-standardised mortality rates (ASMRs) per 100 000 person years and mortality rate ratios were calculated for adults aged 30-74 years old. Poisson regression analysis was performed to assess the independent effects of sex, urban-rural residence and education on drowning mortality. RESULTS: Drowning ASMRs were significantly higher in the Baltic countries than in Finland but declined by nearly 30% in all countries across the study period. There were large inequalities by sex, urban-rural residence and educational level in all countries during 2000-2015. Men, rural residents and low educated individuals had substantially higher drowning ASMRs compared to their counterparts. Absolute and relative inequalities were significantly larger in the Baltic countries than in Finland. Absolute inequalities in drowning mortality declined in all countries across the study period except between urban and rural residents in Finland. Changes in relative inequalities were more variable during 2000-2015. CONCLUSION: Despite a sharp reduction in deaths from drowning in the Baltic countries and Finland in 2000-2015, drowning mortality was still high in these countries at the end of the study period with a substantially larger risk of death seen among men, rural residents and low educated individuals. A concerted effort to prevent drowning mortality among those most at risk may reduce drownings considerably in the general population.

Income differences in partial life expectancy between ages 35 and 64 from 1988 to 2017: the contribution of living arrangements.

BACKGROUND: Socioeconomic differences in mortality among the working-age population have increased in several high-income countries. The aim of this study was to assess whether changes in the living arrangement composition of income groups have contributed to changing income differences in life expectancy during the past 30 years. METHODS: We used Finnish register data covering the total population to calculate partial life expectancies between ages 35 and 64 by income quartile in 1988-2017. The contribution of living arrangements to these differences was assessed by direct standardization. Decomposition methods were used to determine the extent of life expectancy differences due to external (accidental, violent and alcohol-related) causes of death. RESULTS: The life expectancy gap between the highest and lowest income quartile increased until 2003-07, but decreased thereafter. The contribution of living arrangements to these differences remained mostly stable: 36-39% among men and 15-23% among women. Those living without children consistently showed the greatest life expectancy differences by income. External causes of death significantly contributed to income differences in life expectancy. CONCLUSIONS: The living arrangement composition of income groups explained part of the differences in life expectancy, but not their changes. Our results on the contribution of external causes of death imply that both the persistent income gradient in mortality as well as the mortality disparities by living arrangements are at least partially related to similar selection or causal mechanisms.

The relationship of income on stroke incidence in Finland and China.

BACKGROUND: Stroke incidence has continued to increase recently in most countries. The roles of individual-level income on the incidence of overall stroke and its subtypes are still unknown, especially in low- and middle-income countries and the cross-national evidence is also limited. We explored the association between individual-level income and stroke incidence in Finland and China. METHODS: Changde Social Health Insurance Database (N=571 843) and Finnish population register (N=4 046 205) data were used to calculate standard stroke incidence rates, which were employed to assess the absolute incidence difference between income quintiles. Cox regression was used to compare income differences in first-ever stroke incidence. RESULTS: The highest income quintile had lower overall and subtype stroke incidence when compared to lower-income quintiles. The relative difference was more evident in hemorrhagic stroke incidence. After adjusting for age and employment status, the disparity of stroke incidence between the lowest and highest income quintiles was high among both men and women and in Finland and China. The disparity was particularly notable among men: in Finland, the hazard ratio (HR) for hemorrhagic stroke was 0.633 [95% confidence interval (95% CI) 0.576-0.696] and HR 0.572 (95% CI 0.540-0.606) for ischemic stroke. The respective figures were HR 0.452 (95% CI 0.276-0.739) and HR 0.633 (95% CI 0.406-0.708) for China. CONCLUSIONS: Individual-level income is related to overall and subtype stroke incidence. Future studies should explore the causal relationship between individual-level income and stroke incidence.

Educational inequalities in hypothermia mortality in the Baltic countries and Finland in 2000-15.

BACKGROUND: Despite an increased focus on cold-related mortality in recent years, there has been comparatively little research specifically on hypothermia mortality and its associated factors. METHODS: Educational inequalities in hypothermia mortality among individuals aged 30-74 in the Baltic countries (Estonia, Latvia, Lithuania) and Finland in 2000-15 were examined using data from longitudinal mortality follow-up studies of population censuses (the Baltics) and from a longitudinal register-based population data file (Finland). RESULTS: Age-standardized mortality rates (ASMRs) were much higher in the Baltic countries than in Finland across the study period. From 2000-07 to 2008-15, overall ASMRs declined in all countries except among Finnish women. Although a strong educational gradient was observed in hypothermia mortality in all countries in 2000-07, inequalities were larger in the Baltic countries. Between 2000-07 and 2008-15, ASMRs declined in all educational groups except for high-educated women in Finland and low-educated women in Lithuania; the changes however were not always statistically significant. The absolute mortality decline was often larger among the low educated resulting in narrowing absolute inequalities (excepting Lithuania), whereas a larger relative decline among the high educated (excepting Finnish women) resulted in a considerable widening of relative inequalities in hypothermia mortality by 2008-15. CONCLUSION: Although some reduction was observed in absolute educational inequalities in hypothermia mortality in 2000-15, substantial and widening relative inequalities highlight the need for further action in combatting factors behind deaths from excessive cold in socioeconomically disadvantaged groups, including risky alcohol consumption and homelessness.

Pathways into single motherhood, re-partnering, and trajectories of antidepressant medication purchases.

Single motherhood is known to be distressing, and to be associated with poor mental health. However, less is known about the pathways into and out of single motherhood, or about the mental health trajectories of single mothers. We used total population registry data on Finnish women who experienced the life events of separation (616,762), widowhood (43,355), or child birth (515,756) during the 1995-2018 period while between the ages of 15-64. Single mothers were compared with women who experienced the same life event, but without becoming a single mother. The results for women who separated showed that among single mothers, there was a substantial increase in antidepressant use at the time of separation, and only a moderate decline after separation. Among women who experienced widowhood, those who had underage children initially had lower antidepressant use than women without children, but this gap narrowed in the post-widowhood period. In addition, single women experienced more unfavorable mental health trajectories than partnered women around the time they gave birth. Re-partnering was associated with more favorable mental health among all groups of single mothers. Given the growing prevalence of single-parent households, our results underscore the need for context-specific interventions to support single mothers' mental health.

A distributional approach to measuring lifespan stratification.

The study of the mortality differences between groups has traditionally focused on metrics that describe average levels of mortality, for example life expectancy and standardized mortality rates. Additional insights can be gained by using statistical distance metrics to examine differences in lifespan distributions between groups. Here, we use a distance metric, the non-overlap index, to capture the sociological concept of stratification, which emphasizes the emergence of unique, hierarchically layered social strata. We show an application using Finnish registration data that cover the entire population over the period from 1996 to 2017. The results indicate that lifespan stratification and life-expectancy differences between income groups both increased substantially from 1996 to 2008; subsequently, life-expectancy differences declined, whereas stratification stagnated for men and increased for women. We conclude that the non-overlap index uncovers a unique domain of inequalities in mortality and helps to capture important between-group differences that conventional approaches miss.

Income differences in COVID-19 incidence and severity in Finland among people with foreign and native background: A population-based cohort study of individuals nested within households.

BACKGROUND: Although intrahousehold transmission is a key source of Coronavirus Disease 2019 (COVID-19) infections, studies to date have not analysed socioeconomic risk factors on the household level or household clustering of severe COVID-19. We quantify household income differences and household clustering of COVID-19 incidence and severity. METHODS AND FINDINGS: We used register-based cohort data with individual-level linkage across various administrative registers for the total Finnish population living in working-age private households (N = 4,315,342). Incident COVID-19 cases (N = 38,467) were identified from the National Infectious Diseases Register from 1 July 2020 to 22 February 2021. Severe cases (N = 625) were defined as having at least 3 consecutive days of inpatient care with a COVID-19 diagnosis and identified from the Care Register for Health Care between 1 July 2020 and 31 December 2020. We used 2-level logistic regression with individuals nested within households to estimate COVID-19 incidence and case severity among those infected. Adjusted for age, sex, and regional characteristics, the incidence of COVID-19 was higher (odds ratio [OR] 1.67, 95% CI 1.58 to 1.77, p < 0.001, 28.4% of infections) among individuals in the lowest household income quintile than among those in the highest quintile (18.9%). The difference attenuated (OR 1.23, 1.16 to 1.30, p < 0.001) when controlling for foreign background but not when controlling for other household-level risk factors. In fact, we found a clear income gradient in incidence only among people with foreign background but none among those with native background. The odds of severe illness among those infected were also higher in the lowest income quintile (OR 1.97, 1.52 to 2.56, p < 0.001, 28.0% versus 21.6% in the highest quintile), but this difference was fully attenuated (OR 1.08, 0.77 to 1.52, p = 0.64) when controlling for other individual-level risk factors-comorbidities, occupational status, and foreign background. Both incidence and severity were strongly clustered within households: Around 77% of the variation in incidence and 20% in severity were attributable to differences between households. The main limitation of our study was that the test uptake for COVID-19 may have differed between population subgroups. CONCLUSIONS: Low household income appears to be a strong risk factor for both COVID-19 incidence and case severity, but the income differences are largely driven by having foreign background. The strong household clustering of incidence and severity highlights the importance of household context in the prevention and mitigation of COVID-19 outcomes.