Secular trends in the effect of socio-economic factors on birth weight and infant survival in Sweden

The U-Shaped Curve of Health Inequalities Over the 20th and 21st Centuries

This article examines historical trends in health inequalities over the 20th and 21st centuries. Drawing on studies from the United States, United Kingdom, Sweden, and Western Europe, it concludes that there is evidence of a u-shaped curve in (relative) health inequalities. These trends in health inequalities broadly parallel those identified by economists with regards to the u-shaped curve of income and wealth inequalities across the 20th and 21st centuries. The article argues that-as with income inequalities-health inequalities generally decreased across the twentieth century through to the early 1980s. They then started to increase and accelerated further from 2010, particularly in the United Kingdom and the United States. The article sets out four distinct policy periods that shaped the evolution of trends in health inequalities: the Interbellum Era, 1920-1950; the Trente Glorieuse, 1950-1980; Neoliberalism, 1980-2010; and the Crisis Age, 2010-present. The u-shaped curve of health inequalities over this period suggests that social policies, health care access, and political incorporation have driven changes over time. Taking this long view of changes in health inequalities emphasizes the importance of politics and policy for future health improvement.

Effects of maternal education on infant mortality and stillbirths in Denmark

This study examined inequalities in infant mortality in Denmark in relation to maternal educational level, and compared the inequalities to those observed in a similar study 10 years earlier. It was a register-based study of all singleton births in Denmark 1991-92, a study population of 113,814 births. When adjusted for mother's age, parity, and smoking, the stillbirth rate was independent of mother's educational level, but a clear social gradient in infant mortality was observed. Compared with a similar study in 1982-83, infant mortality has decreased most in the highest educational group and has increased in the lowest educational group. In conclusion, social inequality in infant mortality in Denmark is pronounced and cannot be explained by differences in smoking habits. The social gap between different educational groups has widened during the last decade, but may partly be explained by the decreasing number of women in the lowest educational group.

Social determinants for infant mortality in the Nordic countries, 1980 - 2001

Aim: Social equity in health is an important goal of public health policies in the Nordic countries. Infant mortality is often used as an indicator of the health of societies, and has decreased substantially in the Nordic welfare states over the past 20 years. To identify social patterns in infant mortality in this context the authors set out to review the existing epidemiological literature on associations between social indicators and infant mortality in Denmark, Finland, Norway, and Sweden during the period 1980 - 2000. Methods: Nordic epidemiological studies in the databases ISI Web of Science, PubMed, and OVID, published between 1980 and 2000 focusing on social indicators of infant, neonatal, and postneonatal mortality, were identified. The selected keywords on social indicators were: education, income, occupation, social factors, socioeconomic status, social position, and social class. Results: Social inequality in infant mortality was reported from Denmark, Finland, Norway, and Sweden, and it was found that these increased during the study period. Post-neonatal mortality showed a stronger association with social indicators than neonatal mortality. Some studies showed that neonatal mortality was associated with social indicators in a non-linear fashion, with high rates of mortality in both the lowest and highest social strata. The pattern differed, however, between countries with Finland and Sweden showing consistently less social inequalities than Denmark and Norway. While the increased inequality shown in most studies was an increase in relative risk, a single study from Denmark demonstrated an absolute increase in infant mortality among children born to less educated women. Conclusions: Social inequalities in infant mortality are observed in all four countries, irrespective of social indicators used in the studies. It is, however, difficult to draw inferences from the comparisons between countries, since different measures of social position and different inclusion criteria are used in the studies. Nordic collaborative analyses of social gradients in infant death are needed, taking advantage of the population-covering registers in longitudinal designs, to explore the mechanisms behind the social patterns in infant mortality.

An Analysis of the Role of Health Care in Reducing Socioeconomic Inequalities in Health: The Case of the Netherlands

The aim of this article is to analyze the role of the health care system in reducing socioeconomic inequalities in health in countries with good access to health services, using the Dutch example. In the past, health care has contributed substantially to reducing a number of health problems in the population, particularly health problems leading to mortality. Data on trends in mortality from selected conditions by socioeconomic group show that both higher and lower socioeconomic groups have profited from these mortality reductions, probably because of largely equal access to essential health care services, and that absolute inequalities in mortality from these conditions have declined notably. The current situation is still one of largely equal financial access to health care services, with relatively small differences between socioeconomic groups in health care utilization, after adjustment for differences in prevalence of health problems. There is no evidence that inequalities in health care utilization contribute to a widening of socioeconomic inequalities in health. Financing of the health care system, however, is slightly regressive, and out-of-pocket payments contribute to the poor financial situation of the chronically ill. For the future, three possible contributions of the health care system to reducing socioeconomic inequalities in health are described: preservation of equal access to high-quality health care; development of specific care packages for lower socioeconomic groups; promotion and support of intersectoral activities.

Risk factors for low birth weight in Botucatu city, SP state, Brazil: a study conducted in the public health system from 2004 to 2008

BACKGROUND

Low birth weight (LBW), defined as birth weight less than 2500 g, has a complex etiology and may be a result of premature interruption of pregnancy or intrauterine growth restriction. The objective of this study was to provide information on determinants of LBW and contribute to the understanding of the problem in Brazil.

METHODS

A case-control study was conducted in Botucatu city, SP state, Brazil. The study population consisted of 2 groups with 860 newborns in each group as follows: low weight newborns (LWNB) and a control group (weight ≥ 2500 g). Secondary data from 2004 to 2008 were collected using the Live Birth Certificate (LBC) and records from medical charts of pregnant women in Basic Health Units (BHU) and in the Public University Hospital (UH). Variables were as follows: maternal socio-demographic characteristics, pregnancy and birth conditions including quality of prenatal care according to 3 criteria. They were based on parameters established by the Ministry of Health (MH), one of them, the modified Kessner Index. The multivariable analysis by logistic regression was used to evaluate the association between variables and LBW.

RESULTS

According to the analysis, the factors associated with LBW were as follows: prematurity (OR = 56.98, 95% CI 29.52-109.95), twin pregnancy (OR = 20.00, 95% CI 6.25-100.00), maternal smoking (OR = 2.12, 95% CI 1.33-3.45), maternal malnourishment (OR = 2.30, 95% CI 1.08-5.00), maternal obesity (OR = 2.30, 95% IC 1.18-4.48), weight gain during pregnancy less than 5 kg (OR = 2.63, 95% CI 1.35-5.00) and weight gain during pregnancy more than 15 kg (OR = 2.26, 95% CI 1.16-4.41). Adequacy of prenatal care visits adjusted to gestational age was less frequent in the LBW group than in the control group (68.7% vs. 80.5%, x2 p < 0.001). According to the modified Kessner Index, 64.4% of prenatal visits in the LWNB group were adequate.

CONCLUSION

LWNB are a quite heterogeneous group of infants concerning their determinants and prevention actions against LBW and the follow-up of these infants have also been very complex. Therefore, improvement in the quality of care provided should be given priority through concrete actions for prevention of LBW.

Childhood body mass index (BMI), breastfeeding and risk of Type 1 diabetes: findings from a longitudinal national birth cohort

AIMS

To perform a longitudinal analysis of the association between childhood body mass index (BMI) and later risk of Type 1 diabetes, controlling for socio-economic status, birthweight, height in early and late childhood, breastfeeding history and pubertal status.

METHODS

Analysis of the 1970 British Birth Cohort, followed up at age 5, 10 and 30 years (n = 11,261). Data were available on birthweight, breastfeeding; height, weight, pubertal status, socio-economic status at age 10 years; self-report data on history of diabetes (type, age at onset) at age 30 years. Cox proportional hazards models were used to examine relations of childhood growth, socio-economic status and breastfeeding history to the incidence of Type 1 diabetes between 10 and 30 years of age.

RESULTS

Sixty-one subjects (0.5%) reported Type 1 diabetes at 30 years of age; 47 (77%) reported onset >or= age 10 years. Higher BMI z-score at 10 years predicted higher risk of subsequent Type 1 diabetes (hazard ratio 1.8, 95% confidence interval 1.2 to 2.8, P = 0.01) when adjusted for birthweight, pubertal status, breastfeeding history and socio-economic status. Repeating the model for childhood obesity, the hazard ratio was 3.1 (1.0, 9.3; P = 0.05). Birthweight, breastfeeding, height growth and pubertal timing were not associated with incidence of Type 1 diabetes.

CONCLUSIONS

Higher BMI in childhood independently increased the risk of later Type 1 diabetes, supporting suggestions that obesity may provide a link between Type 1 and Type 2 diabetes. This supports observations of a rise in Type 1 diabetes prevalence. Reduction in childhood obesity may reduce the incidence of Type 1 as well as Type 2 diabetes.

Social inequality in fetal and perinatal mortality in the Nordic countries

Aim: The aim of this study is to review the epidemiological literature from the past 27 years on social inequality in fetal and perinatal mortality in the Nordic countries in order to examine whether social inequalities in fetal and perinatal mortality exist, and whether there are differences between the countries. Methods: The databases MEDLINE and EMBASE were searched for Nordic epidemiological studies published between January 1980 and August 2007 about the association between social indicators and the outcomes spontaneous abortion, stillbirth or perinatal mortality. Thirty-five studies that fulfilled the inclusion criteria were identified for this review. Results: Social differences in stillbirth and perinatal mortality were found in all of the identified Finnish and Norwegian studies and in the majority of studies from Denmark, whereas in the Swedish studies the findings were less consistent. As only a small number of studies on spontaneous abortion were identified (n=3), no conclusions were drawn with regard to this outcome. Conclusions: There seems to be a reasonable body of evidence that social inequality in stillbirth and perinatal mortality exists in Norway, Finland and Denmark, whereas the conclusions regarding Sweden are more uncertain. A number of methodological problems complicate the comparison of the findings. Nordic collaborative analyses of social gradients in spontaneous abortion, stillbirth and perinatal mortality, which take these methodological concerns into account, are needed in order to draw inferences across countries.

Social inequality and perinatal health: comparison of three Brazilian cohorts

The objective of the present study was to estimate and compare social inequality in terms of three indicators, i.e., low birth weight (LBW), preterm birth (PTB) and small for gestational age (SGA) birth, in three birth cohorts. Two cohorts were from the city of Ribeirão Preto, where data were collected for all 6748 live born singletons in 1978/79 and for one third of live born singletons (2846) in 1994. The third cohort consisted of 2443 singletons born in São Luís over a period of one year (1997/98). In Ribeirão Preto, LBW and PTB rates increased in all social strata from 1978/79 to 1994. Social inequalities regarding LBW and PTB disappeared since the increase in these rates was more accelerated in the groups with higher educational level. The percentage of SGA infants increased over the study period. Social inequality regarding SGA birth increased due to a more intense increase in SGA births in the strata with lower schooling. In São Luís, in 1997/98 there was no social inequality in LBW or PTB rates, whereas SGA birth rate was higher in mothers with less schooling. We speculate that the more accelerated increase in medical intervention, especially due to the increase in cesarean sections in the more privileged groups, could be the main factor explaining the unexpected increase in LBW and PTB rates in Ribeirão Preto and the decrease or disappearance of social inequality regarding these perinatal indicators in the two cities.

Signs of asphyxia at birth and risk of schizophrenia. Population-based case-control study

BACKGROUND

Previous research has found an association between obstetric complications and schizophrenia, but in many studies the sample size was limited, and no assessment of specific exposures was possible.

AIMS

To assess the role of different complications, and in particular to distinguish between disordered foetal development and hypoxia at birth.

METHOD

From the Stockholm County In-Patient Register and community registers, we identified 524 cases of schizophrenia and 1043 controls, matched for age, gender, hospital and parish of birth. Data on obstetric complications were obtained from birth records.

RESULTS

There was a strong association between signs of asphyxia at birth and schizophrenia (OR 4.4; 95% C11.9-10.3) after adjustment for other obstetric complications, maternal history of psychotic illness and social class.

CONCLUSIONS

Signs of asphyxia at birth are associated with an increased risk of schizophrenia in adults.

Maternal risk factors for cause-specific stillbirth and neonatal death

BACKGROUND

To study specific effects of four maternal risk factors: age, parity, educational level, smoking, for specific causes of stillbirth and neonatal death according to a previously described hierarchic classification.

METHODS

The study is based on 9,785 stillbirths or neonatal deaths among infants born in Sweden, 1983-1995 (n=1,412,754) and identified with various Swedish health registers. Statistical analysis is performed using Mantel-Haenszel analysis.

RESULTS

Some risk factors, known from the literature, were confirmed and could be quantified. In addition, high parity was shown to increase the risk for death associated with multiple births (OR=2.49, 95% CI 2.07-3.01) and low educational level seems to be protective for such death (OR=0.75, 95% CI 0.60-0.93). If the infant is SGA, the risk for death is higher at high than at low parity (1.70, 95% CI 1.19-2.43, and 1.0, 95% CI 1.06-1.15, respectively). Maternal smoking seems to aggravate the placental abruption because the death risk in the presence of abruption increases when the mother smoked (OR = 1.74, 95% CI 45-2.08).

CONCLUSIONS

The study shows that the groups of the classification system used (NICE) differ in their association with known risk factors for stillbirth and neonatal deaths and an analysis based on specific causes of death can therefore unravel risk factors hidden when total mortality is used. The computerized method of classification and the cause-of-death classification developed by us is clearly useful for such analyses which requires large materials.

Objective and subjective assessments of socioeconomic status and their relationship to self-rated health in an ethnically diverse sample of pregnant women

A new measure of subjective socioeconomic status (SES) was examined in relation to self-rated physical health in pregnant women. Except among African Americans, subjective SES was significantly related to education, household income, and occupation. Subjective SES was significantly related to self-rated health among all groups. In multiple regression analyses, subjective SES was a significant predictor of self-rated health after the effects of objective indicators were accounted for among White and Chinese American women; among African American women and Latinas, household income was the only significant predictor of self-rated health. After accounting for the effects of subjective SES on health, objective indicators made no additional contribution to explaining health among White and Chinese American women; household income continued to predict health after accounting for subjective SES among Latinas and African American women.

Socioeconomic differences in health and well-being of children and adolescents in Iceland

STUDY OBJECTIVE

To assess differences in health, healthcare use and well-being of children according to their socioeconomic situation.

DESIGN

Part of a larger cross-sectional survey on health and well-being of children and their parents in the Nordic countries.

SETTING

Iceland.

PARTICIPANTS

A questionnaire was sent to the parents of a nationally representative sample of 3,007 school children aged two to seventeen years.

MAIN RESULTS

The SES indicators used were education and occupation of both parents and the disposable income of the family. Logistic regression models were used for the analysis. Children of lower SES were found to have worse health and well-being than those of higher SES. Children of lower SES appeared to use doctor's services to the same degree as children of higher SES, especially after differences in ill health were taken into account.

CONCLUSION

The association between SES and health status and well-being in adulthood can already be detected in childhood, even in an egalitarian country with a homogeneous population.

Declining perinatal mortality in Finland between 1987 and 1994: contribution of different subgroups

OBJECTIVE

To examine the extent to which the decline in perinatal mortality is attributable to some subgroups, especially to certain birthweight or gestation groups.

STUDY DESIGN

A register study using the Finnish Medical Birth Register for years 1987 to 1994.

RESULTS

Of the overall reduction in perinatal mortality from 8.8 to 6.7 per 1000 births, 78% was due to stillbirths, compared with 22% due to early neonatal deaths. The decline in mortality among infants who weighed under 1500 g at birth was the major contributor (62%) to the overall reduction in perinatal mortality. The largest decline in mortality in the stillbirth group occurred among those weighing < 1000 g, while for early neonatal deaths the group most affected weighed 1000-1499 g. A similar pattern emerged when the gestation-week groups were examined.

CONCLUSION

The decline in perinatal mortality is attributable to stillbirths of very low birthweight. The most likely explanations for this result are the improved antenatal and neonatal care and the wider use of malformation screening.

Adverse pregnancy outcome in schizophrenic women: occurrence and risk factors

Low birth weight and preterm birth are important predictors of infant mortality and morbidity, and may increase the risk of schizophrenia. These adverse outcomes of pregnancy could be associated, therefore, with increased risk in children genetically predisposed to schizophrenia. The aim of this review was to describe the occurrence of risk factors for low birth weight, preterm birth, and perinatal death among schizophrenic women, and to describe the incidence of those adverse pregnancy outcomes among schizophrenic women. Smoking, substance abuse, and low socioeconomic status are associated with fetal growth retardation, preterm birth, and perinatal death, and also with schizophrenia. Therefore, increased incidence of adverse pregnancy outcome should be expected in schizophrenic women. The available evidence suggests that schizophrenic women are at increased risk of delivering infants with low birth weight, but the existing studies are of small statistical power. Preterm birth and perinatal death have only been investigated little among schizophrenic women. An important focus of future research should be to establish the risk of adverse pregnancy outcome, and to study the association between the suspected risk factors and pregnancy outcome in schizophrenic women. In clinical work with pregnant schizophrenic women, efforts should be made to prevent exposure to suspected risk factors like smoking, substance use, and socioeconomic problems. This could possibly decrease the mortality and morbidity, including the risk of schizophrenia in the offspring, and clarify the importance of environmental and genetic factors in the etiology of schizophrenia.

Social class differences in health until the age of seven years among the Finnish 1987 birth cohort

Studies on social class differences in childhood health are controversial partly because of different data collection methods, limited sample sizes and the use of limited numbers of health indicators. The increasing collection of health register data enables the use of such data in social class studies. Our purpose was to investigate social class differences in mortality and morbidity among all children born in Finland in 1987 (N=59,865 liveborns) until the age of seven by using several national health registers, and to study whether perinatal health explains these differences. The follow-up was based on data linkage with six national health registers, with 18 regional registers of mentally disabled children, covering the whole country, and with 38 educational registers of the largest county. Morbidity was measured in terms of a cumulative disease index, the cumulative incidence of asthma, diabetes, epilepsy and intellectual disability, hospitalisations, disease-related welfare benefits and special education. Social class, divided in four groups (I-III, Others) was defined by using the mother's occupation at the time the child was seven years old. Our study showed that register-based data collection is a feasible method for studying social class differences in health. In the unadjusted analysis, social class differences were found for all indicators except mortality after the age of one year and for the cumulative incidence of asthma and diabetes. After adjusting for confounders, the children in the lowest social class had the highest risk for poor health outcome both in the perinatal period and in childhood, and had the most intellectual disabilities, the highest mean of hospitalisation days, and received the most special education. The differences were not explained by perinatal health. The health of the children in the lowest social class was poorer, especially regarding mental indicators.

Low birth weight is associated with elevated systolic blood pressure in adolescence: a prospective study of a birth cohort of 149378 Swedish boys

OBJECTIVES

To determine the association between birth weight and systolic blood pressure (SBP) in male adolescents at the age of 18 years.

DESIGN

A prospective study by means of a register linkage between the Swedish Medical Birth Register and the national register for conscript testing before military service.

METHODS

From the birth registry we collected data on birth weight, gestational age, maternal age and parity for 149378 individuals. At conscript testing, subjects were given a physical examination, and weight, height, and mean blood pressure were recorded after 5-10 min rest.

RESULTS

Mean+/-SD birth weight was 3543+/-551 g after a mean of 39.7+/-2.0 gestational weeks. Mean+/-SD blood pressure at the conscript testing was 128.8+/-10.9/65.2+/-10.6 mmHg. SBP, but not diastolic blood pressure, differed significantly (test for trend, P< 0.001) between birth weight strata (deciles), with a higher SBP in strata with lower birth weight. A difference in birth weight of 1000 g decreased SBP by 0.8 mmHg. This was most pronounced in subjects with a rapid growth development (n = 1057), coming from the lowest decile of birth weight and reaching to the highest decile of body mass index, in a very consistent manner. The odds ratio for being in the top decile of SBP was 1.55 (95% confidence interval 1.32-1.81) for this growth 'catch-up' group compared with the rest of the cohort.

CONCLUSIONS

Birth weight was inversely associated with SBP in a large cohort of young men in their late teens. This supports the notion of a programming effect of fetal growth retardation in utero on haemodynamic regulation in early adult life.

Is smoking in pregnancy interrelated between generations?

In order to compare pregnancy smoking habits in two generations, data on first generation deliveries in 1964-67 were obtained from prospective questionnaires. By record linkage with the Swedish Medical Birth Registry, data on daughters giving second generation births (n = 1659) were obtained, including prospective smoking information. The catchment area was that of Helsingborg County Hospital (population 145,000). Second generation births until December 31, 1993 were identified in all of Sweden. The odds ratio of maternal smoking in the first generation for pregnancy smoking among the daughters was significantly increased and approximately doubled. Adjustment for confounders was made using the Mantel-Haenszel method. Similar odds ratios remained after stratification either for a social environment index of the first generation or the educational level of the second generation. Thus, our data suggest a biological association between pregnancy smoking habits over generations. Research on causative mechanisms could help design more efficient intervention programs. In a separate analysis of two parturient cohorts in Helsingborg 30 y apart, we found that the prevalence of maternal smoking had decreased comparatively more among younger than older women.

Social causes of low birth weight

The manifest importance of reducing the incidence of low birth weight is most obvious for the first year of life: low birth weight is the single most important factor affecting infant morbidity and mortality. However, there is growing evidence that the adverse consequences of low birth weight continue throughout the life cycle. This review deals primarily with social causes of low birth weight.

Methods for the evaluation of social effects on birth weight-- experiences with Swedish population registries

All births in Sweden in 1986, registered in the Medical Birth Registry, were analyzed with linked data from the November 1985 census in order to identify variables which could be used as proxy variables for the socio-economic situation of the women, using birth weight as outcome variable. Two phenomena appear to be strong socio-economic indices of significance for birth weight: whether the woman co-habited or not at the census and whether she had a long education (> 14 years) and an "academic" work. The two variables interacted, however: when the woman had a long education, cohabitation status played no significant role. Maternal education as judged from occupation seemed to play a more important role than paternal education or job. To some extent, the effects of the socio-economic variables could be explained by different smoking habits but a residual effect existed which may have different explanations. Cohabitation status and education may be used as estimates of socio-economic level of significance for birth weight and perhaps other pregnancy outcome in the analysis of, for instance, the effect of various occupational exposures on pregnancy outcome.