Amy Heshmati

Associations Between Birth Characteristics and Eating Disorders Across the Life Course: Findings From 2 Million Males and Females Born in Sweden, 1975–1998

Birth characteristics predict a range of major physical and mental disorders, but findings regarding eating disorders are inconsistent and inconclusive. This total-population Swedish cohort study identified 2,015,862 individuals born in 1975-1998 and followed them for anorexia nervosa, bulimia nervosa, and eating disorder not otherwise specified until the end of 2010. We examined associations with multiple family and birth characteristics and conducted within-family analyses to test for maternal-level confounding. In total, 1,019 males and 15,395 females received an eating disorder diagnosis. Anorexia nervosa was independently predicted by multiple birth (adjusted hazard ratio = 1.33, 95% confidence interval: 1.15, 1.53) for twins or triplets vs. singletons) and lower gestational age (adjusted hazard ratio = 0.96, 95% confidence interval: 0.95, 0.98) per extra week of gestation, with a clear dose-response pattern. Within-family analyses provided no evidence of residual maternal-level confounding. Higher birth weight for gestational age showed a strong, positive dose-response association with bulimia nervosa (adjusted hazard ratio = 1.15, 95% confidence interval: 1.09, 1.22, per each standard-deviation increase), again with no evidence of residual maternal-level confounding. We conclude that some perinatal characteristics may play causal, disease-specific roles in the development of eating disorders, including via perinatal variation within the normal range. Further research into the underlying mechanisms is warranted. Finally, several large population-based studies of anorexia nervosa have been conducted in twins; it is possible that these studies considerably overestimate prevalence.

Family History of Education Predicts Eating Disorders across Multiple Generations among 2 Million Swedish Males and Females

Purpose To investigate which facets of parent and grandparent socio-economic position (SEP) are associated with eating disorders (ED), and how this varies by ED subtype and over time. Methods Total-population cohort study of 1,040,165 females and 1,098,188 males born 1973–1998 in Sweden, and followed for inpatient or outpatient ED diagnoses until 2010. Proportional hazards models estimated associations with parental education, income and social class, and with grandparental education and income. Results 15,747 females and 1051 males in our sample received an ED diagnosis, with rates increasing in both sexes over time. ED incidence in females was independently predicted by greater educational level among the father, mother and maternal grandparents, but parent social class and parental income showed little or no independent effect. The associations with education were equally strong for anorexia nervosa, bulimia nervosa and ED not-otherwise-specified, and had increased over time. Among males, an apparently similar pattern was seen with respect to anorexia nervosa, but non-anorexia ED showed no association with parental education and an inverse association with parental income. Conclusions Family history of education predicts ED in gender- and disorder-specific ways, and in females the effect is observed across multiple generations. Particularly given that these effects may have grown stronger in more recent cohorts, these findings highlight the need for further research to clarify the underlying mechanisms and identify promising targets for prevention. Speculatively, one such mechanism may involve greater internal and external demands for academic success in highly educated families.

Placental weight and foetal growth rate as predictors of ischaemic heart disease in a Swedish cohort

Studies on placental size and cardiovascular disease have shown inconsistent results. We followed 10,503 men and women born in Uppsala, Sweden, 1915-1929 from 1964 to 2008 to assess whether birth characteristics, including placental weight and placenta/birth weight ratio, were predictive of future ischaemic heart disease (IHD). Adjustments were made for birth cohort, age, sex, mothers parity, birth weight, gestational age and social class at birth. Placental weight and birth weight were negatively associated with IHD. The effect of placental weight on IHD was stronger in individuals from medium social class at birth and in those with low education. Men and women from non-manual social class at birth had the lowest risk for IHD as adults. We conclude that low foetal growth rate rather than placental weight was more predictive of IHD in the Swedish cohort. However, the strong effect of social class at birth on risk for IHD did not appear to be mediated by foetal growth rate.

Childhood and adulthood socio-economic position and hypertensive disorders in pregnancy: the Uppsala Birth Cohort Multigenerational Study

Background Childhood and adulthood socio-economic position (SEP) is associated with cardiovascular disease in later life, but associations with hypertensive disorders in pregnancy are not well established. Objective The aim of this study was to investigate the association of childhood and adulthood SEP with hypertensive disorders in pregnancy (chronic hypertension, gestational hypertension and pre-eclampsia/eclampsia). Method Study participants were Swedish women (n=9507) from generation 3 of the Uppsala Birth Cohort Multigenerational Study (UBCoS Multigen) who delivered a live singleton offspring between 1982 and 2008. Social and health data were obtained from routine Swedish registers. Associations of own education (adulthood SEP), and parental education and social class (childhood SEP) with hypertensive disorders were studied using logistic regression with adjustments for age, calendar period, parity, smoking and body mass index. Results Low own education was associated with chronic hypertension, but not with gestational hypertension or pre-eclampsia/eclampsia. Increased risk of chronic hypertension was seen in women whose mothers had medium education compared with women whose mothers had high education (OR 2.18, 95% CI 1.03 to 4.62). Women from a manual social class during childhood had twice the risk of chronic hypertension compared with those from non-manual backgrounds (OR 2.19, 95% CI 1.28 to 3.75). Childhood SEP was not associated with gestational hypertension or pre-eclampsia/eclampsia. Conclusions Childhood and adulthood SEP was associated with chronic hypertension in pregnancy. In contrast, no association with childhood or adulthood SEP was seen for gestational hypertension or pre-eclampsia/eclampsia.

Social patterning of overeating, binge eating, compensatory behaviours and symptoms of bulimia nervosa in young adult women: results from the Australian Longitudinal Study on Women’s Health

Objective To study social patterning of overeating and symptoms of disordered eating in a general population. Design A representative, population-based cohort study. Setting The Australian Longitudinal Study on Women’s Health (ALSWH), Survey 1 in 1996 and Survey 2 in 2000. Subjects Women (n 12 599) aged 18–23 years completed a questionnaire survey at baseline, of whom 6866 could be studied prospectively. Results Seventeen per cent of women reported episodes of overeating, 16 % reported binge eating and 10 % reported compensatory behaviours. Almost 4 % of women reported symptoms consistent with bulimia nervosa. Low education, not living with family, perceived financial difficulty (OR=1·8 and 1·3 for women with severe and some financial difficulty, respectively, compared with none) and European language other than English spoken at home (OR=1·5 for European compared with Australian/English) were associated with higher prevalence of binge eating. Furthermore, longitudinal analyses indicated increased risk of persistent binge eating among women with a history of being overweight in childhood, those residing in metropolitan Australia, women with higher BMI, smokers and binge drinkers. Conclusions Overeating, binge eating and symptoms of bulimia nervosa are common among young Australian women and cluster with binge drinking. Perceived financial stress appears to increase the risk of binge eating and bulimia nervosa. It is unclear whether women of European origin and those with a history of childhood overweight carry higher risk of binge eating because of genetic or cultural reasons.

Maternal pelvic size, fetal growth and risk of stroke in adult offspring in a large Swedish cohort

Earlier research suggests that maternal pelvic size is associated with offsprings stroke risk in later life. We followed 6362 men and women from Uppsala, Sweden, born between 1915 and 1929 from 1964 to 2008 to assess whether maternal pelvic size was associated with incidence of thrombotic stroke (TS), haemorrhagic stroke (HS) and other stroke (OS). Offspring whose mothers had a flat pelvis had lower birth weight and birth-weight-for-gestational-age compared with those who did not. Inverse linear associations of birth-weight-for-gestational-age were observed with TS and OS. Female offspring whose mothers had a flat pelvis had increased risk of TS, but flat pelvis was not associated with other types of stroke. A smaller difference between intercristal and interspinous diameters and a smaller external conjugate diameter were independently associated with HS, whereas no pelvic measurements were associated with OS. We conclude that a smaller pelvis in women may impact the health of their offspring in adulthood.

Early life characteristics, social mobility during childhood and risk of stroke in later life: findings from a Swedish cohort.

Aims: To investigate if early life characteristics and social mobility during childhood are associated with incident thrombotic stroke (TS), haemorrhagic stroke (HS) and other stroke (OS). Methods: Our study population consists of all live births at Uppsala University Hospital in 1915–1929 (Uppsala Birth Cohort; n = 14,192), of whom 5532 males and 5061 females were singleton births and lived in Sweden in 1964. We followed them from 1 January 1964 until first diagnosis of stroke (in the National Patient Register or Causes of Death Register), emigration, death, or until 31 December 2008. Data were analysed using Cox regression, stratifying by gender. Results: Gestational age was negatively associated with TS and OS in women only. Women had increased risk of TS if they were born early preterm (<35 weeks) (HR 1.54 (95% CI 1.02–2.31)) or preterm (35–36 weeks) (HR 1.37 (95% CI 1.03–1.83)) compared to women born at term. By contrast, only women who were early preterm (HR 1.98 (95% CI 1.27–3.10) had an increased risk of OS. Men who were born post-term (⩾42 weeks) had increased risk of HS (HR 1.45 (95% CI 1.04–2.01)) compared with men born at term, with no association for women. TS was associated with social mobility during childhood in women: women whose families were upwardly or downwardly mobile had increased risk of TS compared to women who were always advantaged during childhood. Conclusions: Gestational age and social mobility during childhood were associated with increased risk of stroke later in life, particularly among women, but there was some heterogeneity between stroke subtypes.

PL03 Associations between Birth Characteristics and Eating Disorders Across the Life Course: Findings from two Million Males and Females Born in Sweden 1975-1998

Background Recent years have seen considerable interest in the developmental origins of eating disorders (ED) but results have been conflicting, perhaps reflecting low power in many studies. Limited power has also prevented robust comparisons of associations with ED subtypes or the use of within-family designs to address the potential for confounding. Methods We used total population data to create a cohort of 2,011,908 males and females, born 1975-1998 in Sweden to Swedish-born mothers. Birth characteristics included twin/triplet status; gestational age; birthweight; birth length; premature rupture of the membranes; delivery method; Apgar score at 5 minutes; birth traumas; mother’s smoking during pregnancy; and mother’s weight gain during pregnancy. We adjusted for multiple family and social characteristics, and conducted within-family analyses to test for confounding at the maternal/family level. Our outcomes were hospitalisation for anorexia, bulimia or eating disorder not-otherwise-specified (EDNOS)’ after age 12, with follow-up period until end 2010. Results Anorexia was independently predicted by multiple birth (AOR 1.33 [95% CI 1.15, 1.53] for twin/triplet vs. singleton) and lower gestational age (HR 0.96 [0.95, 0.98] per extra week of gestation). Gestational age showed a clear dose-response pattern. These associations were largely specific to anorexia, and were only seen in the cohort members affected; within-family analyses revealed that the maternal siblings of twins or preterm individuals showed no increased risk, and provided no evidence of residual maternal-level confounding. Higher birthweight for gestational age showed a strong, positive dose-response association with bulimia (HR 1.15 [1.09, 1.22]) per sex-standardised standard deviation increase). Again, this association was specific to bulimia and within-family analyses provided no evidence of residual confounding. By contrast, although mother’s smoking predicted anorexia, this did seem likely to reflect maternal-level confounding. Other birth characteristics showed little or no association with any ED outcome, except a trend towards increased bulimia and EDNOS among mothers who gained excessive weight during pregnancy. Conclusion These findings are consistent with a causal role of earlier gestational age upon anorexia and higher birthweight upon bulimia. Further research is needed to elucidate the mechanisms, but the dose-response nature of these associations indicates that they do not simply reflect pathological responses at the extremes of the distribution. The strong association with multiple births is noteworthy as many of the largest population-based studies of ED prevalence have been conducted in twins: our findings suggest the possibility that such studies substantially overestimate ED prevalence.