Comorbidities in women with polycystic ovary syndrome: a sibling study.

BACKGROUND: Polycystic ovary syndrome (PCOS) has previously been associated with several comorbidities that may have shared genetic, epigenetic, developmental or environmental origins. PCOS may be influenced by prenatal androgen excess, poor intrauterine or childhood environmental factors, childhood obesity and learned health risk behaviors. We analyzed the association between PCOS and several relevant comorbidities while adjusting for early-life biological and socioeconomic conditions, also investigating the extent to which the association is affected by familial risk factors. METHODS: This total-population register-based cohort study included 333,999 full sisters, born between 1962 and 1980. PCOS and comorbidity diagnoses were measured at age 17-45 years through national hospital register data from 1997 to 2011, and complemented with information on the study subjects´ early-life and social characteristics. In the main analysis, sister fixed effects (FE) models were used to control for all time-invariant factors that are shared among sisters, thereby testing whether the association between PCOS and examined comorbidities is influenced by unobserved familial environmental, social or genetic factors. RESULTS: Three thousand five hundred seventy women in the Sister sample were diagnosed with PCOS, of whom 14% had obesity, 8% had depression, 7% had anxiety and 4% experienced sleeping, sexual and eating disorders (SSE). Having PCOS increased the odds of obesity nearly 6-fold (adjusted OR (aOR): 5.9 [95% CI:5.4-6.5]). This association was attenuated in models accounting for unobserved characteristics shared between full sisters, but remained considerable in size (Sister FE: aOR: 4.5 [95% CI: 3.6-5.6]). For depression (Sister FE: aOR: 1.4 [95% CI: 1.2-1.8]) and anxiety (Sister FE: aOR: 1.5 [95% CI: 1.2-1.8), there was a small decrease in the aORs when controlling for factors shared between sisters. Being diagnosed with SSE disorders yielded a 2.4 aOR (95% CI:2.0-2.6) when controlling for a comprehensive set of individual-level confounders, which only decreased slightly when controlling for factors at the family level such as shared genes or parenting style. Accounting for differences between sisters in observed early-life circumstances influenced the estimated associations marginally. CONCLUSION: Having been diagnosed with PCOS is associated with a markedly increased risk of obesity and sleeping, sexual and eating disorders, also after accounting for factors shared between sisters and early-life conditions.

Early Life Factors and Polycystic Ovary Syndrome in a Swedish Birth Cohort.

Polycystic ovary syndrome (PCOS) is a medical condition with important consequences for women's well-being and reproductive outcomes. Although the etiology of PCOS is not fully understood, there is increasing evidence of both genetic and environmental determinants, including development in early life. We studied a population of 977,637 singleton women born in in Sweden between 1973 and 1995, followed sometime between the age 15 and 40. The incidence of PCOS was measured using hospital register data during 2001-2012, complemented with information about the women's, parents' and sisters' health and social characteristics from population and health care registers. Cox regression was used to study how PCOS is associated with intergenerational factors, and a range of early life characteristics. 11,594 women in the study sample were diagnosed with PCOS during the follow-up period. The hazard rate for PCOS was increased 3-fold (HR 2.98, 95% CI 2.43-3.64) if the index woman's mother had been diagnosed with PCOS, and with 1.5-fold (HR 1.51, 95% CI 1.39-1.63) if their mother had diabetes mellitus. We found associations of PCOS with lower (<7) one-minute Apgar score (HR 1.19, 95% CI 1.09-1.29) and with post-term birth (HR 1.19, 95% CI 1.13-1.26). Furthermore, heavy (10+ cigarettes/day) maternal smoking (HR 1.30, 95% CI 1.18-1.44) and maternal obesity (HR 1.90, 95% CI 1.62-2.36) were strongly associated with PCOS. This study finds support for the heritability and fetal origins of PCOS. Risk of PCOS could be reduced by further emphasizing the importance of maternal and early life health.

Childhood Growth and Socioeconomic Outcomes in Early Adulthood Evidence from the Inter-War United States.

Childhood malnutrition and its later life effects were important concerns in European and North American social policy in the early twentieth century. However, there have been few studies of the long-term socioeconomic consequences of malnutrition in childhood. We use a unique longitudinal dataset to provide credible causal estimates of the effects of childhood nutrition on early-adult educational and employment outcomes. Our dataset includes 2,499 children in Saint Paul, Minnesota who were weighed and measured in a national children's health survey in 1918/1919 at 0-6 years of age. We observe those same people in the 1920, 1930 and 1940 U.S. censuses allowing us to measure childhood socioeconomic status (1920), adolescent school attendance (1930) and early-adult wages, and employment and educational attainment (1940). Examining variation between biological siblings, we are able to obtain credibly causal estimates of the relationship between childhood stature and weight and later life outcomes, largely canceling out the bias otherwise resulting from their joint correlation with genes and socioeconomic background. Because the initial survey located children within households, we identify the effect of differences in early childhood nutrition from differences between male siblings. Consistent with contemporary evidence from developing countries we find that being taller and heavier in early childhood is associated with better educational and labor market outcomes. Identifying all effects within families to control for socioeconomic background and family structure we find a standard deviation increase in BMI in early childhood was associated with a 3% increase in weekly earnings and that boys who were heavier for their age at the initial survey were 10% less likely to be unemployed in 1940. Taken together, these results confirm the importance of investments in early life health for later-life outcomes.

Early life exposure to cigarette smoking and adult and old-age male mortality: Evidence from linked US full-count census and mortality data.

BACKGROUND: Smoking is a leading cause of premature death across contemporary developed nations, but few longitudinal individual-level studies have examined the long-term health consequences of exposure to smoking. OBJECTIVE: We examine the effect of fetal and infant exposure to exogenous variation in smoking, brought about by state-level cigarette taxation, on adulthood and old-age mortality (ages 55-73) among cohorts of boys born in the United States during the 1920s and 1930s. METHODS: We use state-of-the-art methods of record linkage to match 1930 and 1940 US full-count census records to death records, identifying early life exposure to the implementation of state-level cigarette taxes through contemporary sources. We examine a population of 2.4 million boys, estimating age at death by means of OLS regression, with post-stratification weights to account for linking selectivity. RESULTS: Fetal or infant exposure to the implementation of state cigarette taxation delayed mortality by about two months. Analyses further indicate heterogenous effects that are consistent with theoretical expectations; the largest benefits are enjoyed by individuals with parents who would have been affected most by the tax implementation. CONCLUSIONS: Despite living in an era of continuously increasing cigarette consumption, cohorts exposed to a reduction in cigarette smoking during early life enjoyed a later age at death. While it is not possible to comprehensively assess the treatment effect on the treated, the magnitude of the effect should not be underestimated, as it is larger than the difference between having parents belonging to the highest and lowest socioeconomic groups. CONTRIBUTION: The study provides the first estimates of long-run health effects from early life exposure to cigarette smoking.

"You're Not from Around Here:" Regional Naming and Life Outcomes.

We examine the socioeconomic consequences of discrimination against people of Southern origins during the U.S. Great Migration of the first half of the 20th century. We ask whether people living in the American North and Midwest in 1940 fared worse with respect to education, occupation, and income if they were perceived to be of Southern origins. We also assess variation in these effects across racial groups and across actual region of origin groups. Using linked data from the 1920 and 1940 U.S. Censuses, we compare the life outcomes of about half a million pairs of brothers who differed with respect to the regional origin implied by their first names. For both whites and blacks, we find statistically significant associations between outcomes and the regional origin implied by names; regardless of where they were born, men living in the North or Midwest in 1940 did worse if their names implied Southern origins. However, these associations are entirely confounded by family-specific cultural, socioeconomic, and other factors that shaped both family naming practices and life outcomes. This finding-that regional discrimination in the early 20th century U.S. did not happen based on names-contrasts sharply with findings from research in more recent years that uses names as proxies for people's risk of exposure to various forms of discrimination. Whereas names are a basis for discrimination in modern times, they were not a basis for regional discrimination in an era in which people had more immediate and direct evidence about regional origins.

Does participating in a long-term cohort study impact research subjects' longevity? Experimental evidence from the Wisconsin Longitudinal Study.

There is considerable evidence that the act of participating in a survey can alter participants' attitudes, behaviors, and other outcomes in meaningful ways. Considering findings that this form of panel conditioning also impacts health behaviors and outcomes, we investigated the effect of participating in an intensive half-century-long cohort study on participants' longevity. To do so, we used data from a 1957 survey of more than 33,000 Wisconsin high school seniors linked to mortality records. One third of those people were selected at random to participate in the Wisconsin Longitudinal Study (WLS); the other two thirds were never again contacted. Our survival models show no evidence of panel conditioning effects on longevity: People selected at random to participate in the WLS had the same mortality outcomes as their peers who were not selected. This finding holds for the full sample, for women, for men, for population subgroups defined by family socioeconomic origins and educational experiences, and for treatment compliers.

Racial Disparities in Mortality During the 1918 Influenza Pandemic in United States Cities.

Against a backdrop of extreme racial health inequality, the 1918 influenza pandemic resulted in a striking reduction of non-White to White influenza and pneumonia mortality disparities in United States cities. We provide the most complete account to date of these reduced racial disparities, showing that they were unexpectedly uniform across cities. Linking data from multiple sources, we then examine potential explanations for this finding, including city-level sociodemographic factors such as segregation, implementation of nonpharmaceutical interventions, racial differences in exposure to the milder spring 1918 "herald wave," and racial differences in early-life influenza exposures, resulting in differential immunological vulnerability to the 1918 flu. While we find little evidence for the first three explanations, we offer suggestive evidence that racial variation in childhood exposure to the 1889-1892 influenza pandemic may have shrunk racial disparities in 1918. We also highlight the possibility that differential behavioral responses to the herald wave may have protected non-White urban populations. By providing a comprehensive description and examination of racial inequality in mortality during the 1918 pandemic, we offer a framework for understanding disparities in infectious disease mortality that considers interactions between the natural histories of particular microbial agents and the social histories of those they infect.

A New Strategy for Linking U.S. Historical Censuses: A Case Study for the IPUMS Multigenerational Longitudinal Panel.

This paper presents a probabilistic method of record linkage, developed using the U.S. full count censuses of 1900 and 1910 but applicable to many sources of digitized historical records. The method links records using a two-step approach, first establishing high confidence matches among men by exploiting a comprehensive set of individual and contextual characteristics. The method then proceeds to link both men and women by leveraging links between households established in the first step. While only the first stage links can be directly comparable to other popular methods in research on the U.S., our method yields both considerably higher linkage rates and greater accuracy while only performing negligibly worse than other algorithms in resembling the target population.

The Influence of Kin Proximity on the Reproductive Success of American Couples, 1900-1910.

Children require a large amount of time, effort, and resources to raise. Physical help, financial contributions, medical care, and other types of assistance from kin and social network members allow couples to space births closer together while maintaining or increasing child survival. We examine the impact of kin availability on couples' reproductive success in the early twentieth-century United States with a panel data set of over 3.1 million couples linked between the 1900 and 1910 U.S. censuses. Our results indicate that kin proximity outside the household was positively associated with fertility, child survival, and net reproduction, and suggest that declining kin availability was an important contributing factor to the fertility transition in the United States. We also find important differences between maternal and paternal kin inside the household-including higher fertility among women residing with their mother-in-law than among those residing with their mother-that support hypotheses related to the contrasting motivations and concerns of parents and parents-in-law.

The Effects of Education on Mortality: Evidence From Linked U.S. Census and Administrative Mortality Data.

Does education change people's lives in a way that delays mortality? Or is education primarily a proxy for unobserved endowments that promote longevity? Most scholars conclude that the former is true, but recent evidence based on Danish twin data calls this conclusion into question. Unfortunately, these potentially field-changing findings-that obtaining additional schooling has no independent effect on survival net of other hard-to-observe characteristics-have not yet been subject to replication outside Scandinavia. In this article, we produce the first U.S.-based estimates of the effects of education on mortality using a representative panel of male twin pairs drawn from linked complete-count census and death records. For comparison purposes, and to shed additional light on the roles that neighborhood, family, and genetic factors play in confounding associations between education and mortality, we also produce parallel estimates of the education-mortality relationship using data on (1) unrelated males who lived in different neighborhoods during childhood, (2) unrelated males who shared the same neighborhood growing up, and (3) non-twin siblings who shared the same family environment but whose genetic endowments vary to a greater degree. We find robust associations between education and mortality across all four samples, although estimates are modestly attenuated among twins and non-twin siblings. These findings-coupled with several robustness checks and sensitivity analyses-support a causal interpretation of the association between education and mortality for cohorts of boys born in the United States in the first part of the twentieth century.

When Did the Health Gradient Emerge? Social Class and Adult Mortality in Southern Sweden, 1813-2015.

Across today's developed world, there is a clear mortality gradient by socioeconomic status for all ages. It is often taken for granted that this gradient was as strong-or even stronger-in the past when social transfers were rudimentary and health care systems were less developed. Some studies based on cross-sectional data have supported this view, but others based on longitudinal data found that this was not the case. If there was no gradient in the past, when did it emerge? To answer this question, we examine social class differences in adult mortality for men and women in southern Sweden over a 200-year period, using unique individual-level register data. We find a systematic class gradient in adult mortality emerging at ages 30-59 only after 1950 for women and after 1970 for men, and in subsequent periods also observable for ages 60-89. Given that the mortality gradient emerged when Sweden transitioned into a modern welfare state with substantial social transfers and a universal health care system, this finding points to lifestyle and psychosocial factors as likely determinants.

Time and Generation: Parents' Integration and Children's School Performance in Sweden, 1989-2011.

A central element of assimilation theory is that increasing time and number of previous immigrant generations in a host country leaves immigrants and their children more integrated and capable of navigating the host society. However, the underperformance of some immigrant groups in Sweden calls into question this relationship. Additionally, many studies regard intermarriage as an outcome of immigrant integration and rarely investigate whether integration continues after intermarriage. Using population level data from the Swedish interdisciplinary panel on 22 cohorts of ninth-grade students born between 1973 and 1995, we examine the effect of parents' time in Sweden on their children's grade point average using family fixed effects. Additionally, we investigate whether this relationship differs between "2.0" and "2.5" generation children. We find, generally, that parents' time in Sweden increases their children's educational performance, though some variation by parents' region of origin exists. This supports the idea that integration experiences in immigrant families can be transmitted across generations. Further, this generally holds for both the 2.0 and 2.5 generation children. This relationship among the 2.5 generation is notable as previous studies using a family-based approach looking at the intergenerational transmission of integration have largely focused on the children of two foreign-born parents.

The Long-Lasting Influenza: The Impact of Fetal Stress During the 1918 Influenza Pandemic on Socioeconomic Attainment and Health in Sweden, 1968-2012.

The 1918 influenza pandemic had not only a massive instant death toll but also lasting effects on its survivors. Several studies have shown that children born in 1919, and thus exposed to the H1N1 virus in utero, experienced worse health and socioeconomic outcomes in older ages than surrounding birth cohorts. This study combines several sources of contemporary statistics with full-population individual-level data for Sweden during 1968-2012 to examine the influence of fetal exposure to the Spanish flu on health, adulthood income, and occupational attainment. For both men and women, fetal exposure resulted in higher morbidity in ages 54-87, as measured by hospitalization. For males, exposure during the second trimester also affected mortality in cancer and heart disease. Overall, the effects on all-cause mortality were modest, with about three months shorter remaining life expectancy for the cohorts exposed during the second trimester. For socioeconomic outcomes, results fail to provide consistent evidence supporting any long-term consequences of fetal exposure. We conclude that although the immediate health effects of exposure to the 1918 pandemic were huge, the long-term effects were modest in size.

Resolved Parental Infertility and Children's Educational Achievement.

Although difficulty conceiving a child has long been a major medical and social preoccupation, it has not been considered as a predictor of long-term outcomes in children ultimately conceived. This is consistent with a broader gap in knowledge regarding the consequences of parental health for educational performance in offspring. Here we address that omission, asking how resolved parental infertility relates to children's academic achievement. In a sample of all Swedish births between 1988 and 1995, we find that involuntary childlessness prior to either a first or a second birth is associated with lower academic achievement (both test scores and GPA) in children at age 16, even if the period of infertility was prior to a sibling's birth rather than the child's own. Our results support a conceptualization of infertility as a cumulative physical and social experience with effects extending well beyond the point at which a child is born, and emphasize the need to better understand how specific parental health conditions constrain children's educational outcomes.

Early life conditions and long-term sickness absence during adulthood--a longitudinal study of 9000 siblings in Sweden.

This study examines the influence of health conditions experienced during the individual's first year of life on the incidence of sickness absence during adulthood. Using a sample of approximately 9000 biological siblings from 17 countries of origin and living in Sweden during the time period 1981-1991, sibling fixed effect models are estimated. This approach is combined with the use of an exogenous measurement of early life conditions, operationalized as the infant mortality rate. The link between early life conditions and later life outcomes is examined both with and without intermediary characteristics observed during the individual's childhood and adulthood, aiming for a better understanding regarding to what extent the effect of exposure to an early life insult can be mediated. The results suggest that exposure to worse health conditions during the first year of life is associated with an elevated risk of experiencing sickness absence during adulthood. An increase in infant mortality rate by ten per thousand is associated with a four percentage point higher probability of experiencing sickness absence. Despite the importance of adulthood socioeconomic status on sickness absence propensity, these factors do not mediate the influence from the health conditions experienced during the first year of life, suggesting that the association from early life conditions on sickness absence in adulthood operates as a direct mechanism. The link between early life conditions and sickness absence is only present for children to parents with primary schooling and not for individuals with more educated parents. These findings suggest that families with more abundant resources have the ability to protect their child from exposure to adverse health conditions during early life, or to cancel out the influence from an early life insult.

Small for gestational age and adulthood risk of disability pension: the contribution of childhood and adulthood conditions.

Early exiting from the labor force and into disability pension (DP) represents a major social problem in Sweden and elsewhere. We examined how being asymmetric (A-SGA) or symmetric (S-SGA) small for gestational age predicts transitioning into DP. We analyzed a longitudinal sample of 8125 men and women from the Stockholm Birth Cohort (SBC), born in 1953 and not on DP in 1990. The SBC consists of data from various sources, including self-reported information and data from administrative registers. The follow-up period was from 1991 to 2009. Yearly information on the receipt of DP benefits from register data was operationalized as a dichotomous variable. 13 percent of the sample moved into DP during follow-up. Cox proportional hazards regression was used to examine whether disadvantageous fetal growth--A-SGA and S-SGA--predicted DP. Men and women born A-SGA had a substantially increased hazard of DP. The full model suggested a hazard ratio of 1.68 (CI: 1.11-2.54), only being affected slightly by adulthood conditions. Several childhood conditions were also associated with DP. Such factors, however, mainly affected DP risk through adulthood conditions. The effect of SGA on DP appeared particularly strong among individuals from socioeconomically disadvantaged backgrounds. The evidence presented suggests that being A-SGA influences the risk of DP, independent of childhood and adulthood conditions, and similarly for men and women. Due to A-SGA being rather infrequent, reducing the occurrence of A-SGA would, however, only have a marginal impact on the stock of DP pensioners. For the individual affected, the elevation in the risk of DP was nevertheless substantial. Other childhood conditions exercised a larger influence on the stock of DP recipients, but they mostly operated through adulthood attainment. The importance of socioeconomic resources in childhood for the long term health consequences of SGA is interesting from a policy perspective and warrants further research.

Relative deprivation and sickness absence in Sweden.

BACKGROUND: A high prevalence of sickness absence in many countries, at a substantial societal cost, underlines the importance to understand its determining mechanisms. This study focuses on the link between relative deprivation and the probability of sickness absence. METHODS: 184,000 men and women in Sweden were followed between 1982 and 2001. The sample consists of working individuals between the ages of 19 and 65. The outcome is defined as experiencing more than 14 days of sickness absence during a year. Based on the complete Swedish population, an individual's degree of relative deprivation is measured through income compared to individuals of the same age, sex, educational level and type. In accounting for the possibility that sickness absence and socioeconomic status are determined by common factors, discrete-time duration models were estimated, accounting for unobserved heterogeneity through random effects. RESULTS: The results confirm that the failure to account for the dynamics of the individual's career biases the influence from socioeconomic characteristics. Results consistently suggest a major influence from relative deprivation, with a consistently lower risk of sickness absence among the highly educated. CONCLUSIONS: Altering individual's health behavior through education appears more efficient in reducing the reliance on sickness absence, rather than redistributive policies.