Socio-economic factors and feto-infant mortality.

During this century, improvements in fetal and infant mortality have been dramatic in the western world, mainly as a result of improved socio-economic conditions. Relative to many other developed countries, the decrease has been more dramatic in the Nordic countries. Population-based health registries exist in all Nordic countries. By record-linkage between birth registries and census data, it is possible to perform population-based studies on the association between social factors and feto-infant mortality. Such studies have recently been carried out in Denmark, Finland, Norway and Sweden and socio-economic differences in late fetal and postneonatal death rates were seen. Death rates as well as the relative importance of socio-economic factors differed between these countries. In Norway, infants delivered by women with 9 years or less of schooling faced an almost three-fold increased risk of dying postneonatally as compared to infants delivered by women with at least 12 years of education. In order to successfully decrease the socio-economic differences in feto-infant mortality between and within the Nordic countries, it is necessary to analyse possible preventable risk factors that are distributed unevenly not only in different socio-economic groups but also between the Nordic countries.     

A New Method for Measuring Misclassification of Maternal Sets in Maternally Linked Birth Records: True and False Linkage Proportions

OBJECTIVES: Numerous studies have used maternally linked birth records to investigate perinatal outcomes, maternal behaviors, and the quality of vital records birth data. Little attention has been given to assessing errors in the linkages and to understanding how such errors affect estimates derived from the linked data. The author developed a framework for conceptualizing maternal linkage error and measures for quantifying it, and examined the behavior of the new measures in a maternally linked file. METHODS: Linkage errors were conceptualized as misclassification, with the classes being the maternal sets (records classified as representing different births to the same woman). The true linkage proportion, analogous to sensitivity, was used to capture the degree to which all of a woman's births were assigned to a single maternal set; the false linkage proportion, analogous to specificity, was used to capture the degree to which the assigned maternal sets combined births from different women. The behavior of the two proportions was examined by introducing increasing degrees of linkage error into a maternally linked file. RESULTS: Both measures indicated greater misclassification with increasing simulated linkage errors. CONCLUSIONS: The new measures may be a useful tool for assessing the quality of maternally linked data, as well as other types of linked records where the linkages are within a single file. This is a necessary step towards developing methods for addressing misclassification bias in studies of maternally linked records through sensitivity analysis, adjustment, and other means.     

Nordic Medical Birth Registers in epidemiological research

This review discusses the use of Nordic Medical Birth Registers (MBRs) in epidemiological studies, paying special attention to the topics that have been investigated and to other data sources that increase the usefulness of MBRs. We divided the reviewed studies into four groups according to the data sources on which they were based: (1) studies using MBR data only; (2) studies combining maternal or paternal background information, obtained from other data sources, with MBR data; (3) studies combining MBR data with subsequent outcome information on newborns; and (4) studies using information about consecutive pregnancies and generations. Our review shows that MBRs are good sources for studying the following topics: maternal biological and obstetric background; interventions and health care during pregnancy and birth; newborns' short-term outcome; and the relations between these factors. In addition, the usefulness of MBRs increases when the data they contain are combined with data from other sources. We found that data from more than twenty different sources have been linked with MBR data in the Nordic counties. As time passes, national MBRs become a useful source of information for studies on consecutive pregnancies or generations. In addition, the associations between pregnancy, delivery, perinatal health and long-term outcome can be studied by using an MBR as the basic data source.     

Perinatal factors reported by mothers: do they agree with medical records?

As perinatal events have been linked with diseases of later onset, epidemiological studies on child development and adult health require information on the perinatal period. When national neonatal registers do not exist, review of medical records may be impractical. However, neonatal information could be obtained by asking mothers to complete a postal questionnaire using data from the Personal Child Health Record (PCHR). We assessed agreement between medical records and mothers' reports for information on delivery and the newborn's condition at birth, based on the PCHR, a short time after delivery. Of 711 women giving birth in 3 French hospitals and invited to participate in the study, 580 (82%) completed a postal questionnaire 6 weeks after delivery, copying the data recorded in the PCHR when available. Information on pregnancy, delivery and the newborn's health at birth was independently extracted from medical records by physicians of the maternity departments. Agreement between medical records and maternal reports for a range of perinatal factors was assessed in 580 newborn-mother dyads using kappa coefficients. Agreement was excellent for first and second stages of delivery, gestational age, birth weight, birth size and head circumference (kappa coefficients 0.80-1.00) and good for hospitalization during pregnancy, but poor for Apgar scores. With this exception, mothers' reports appeared reliable when compared with medical records. As PCHRs exist in most developed countries, this approach could be used in epidemiological studies on child development to increase the reliability of mothers' reports of their newborn's condition at birth.     

Quality of life among children in the Nordic countries

Quality of life (QOL) is a concept with no generally accepted definition. Most clinical studies have had an individual approach where demographic and socioeconomic population aspects have not been considered. QOL has hardly ever been used in studies of children. In this study QOL is defined as the essential resources of a child population, expressed in external, inter-personal and personal conditions. Both objective conditions and the corresponding subjective perceptions are included. A model for an empirical application is demonstrated on a random sample of 15,000 children in the five Nordic countries. The data were collected in a questionnaire mailed to the families of the children. The QOL was analysed in a normative way, where a base value was defined for each variable and the conditions of the children were compared to a Nordic standard for children's QOL. The results showed that children in the Nordic countries have a high QOL. The differences between the countries were rather small. Children in Sweden had the highest QOL, closely followed by children in Denmark and Norway, while children in Finland were in an intermediate position and the Icelandic children had the lowest QOL, mainly due to a lower level of satisfaction. This study can be considered as a base line study which later can be used in studies of time trends or in comparisons of groups of children such as children with special needs.     

Income-related health inequalities in the Nordic countries: examining the role of education, occupational class, and age

Numerous studies have concluded that people's socioeconomic position is related to mortality and morbidity, but that the strength of this association varies considerably both within and between European regions. This has spurred several researchers to more closely examine educational and occupational gradients in health in the Nordic countries to clarify the causes of cross-national differences. However, comparable studies using income as an indicator of socioeconomic position are still lacking. This study uses recent and highly comparable data to fill this gap. The aim of this study is threefold. First, we ask to what extent there is an income gradient in health in the Nordic countries, and to what extent the association differs between these countries. Second and third, we examine whether differences in the attenuation of the income gradient by education and occupational class, and age-specific differences between countries, may act as explanations for differences in the income gradient between the Nordic countries. The data source are three waves of the European Social Survey (ESS, 2002/2004/2006), which included 17,801 people aged 25 and over from Denmark, Finland, Norway, and Sweden. Two subjective health measures (physical/mental self reported health and limiting longstanding illness) were analysed by means of logistic regression. The results show that, in all countries, people reported significantly better health and were less likely to suffer from longstanding illness as they had a higher income. This association is strongest in Norway and Finland and weakest in Denmark. The income gradient in health, but not country differences in this gradient, is partly explained by education and occupational class. Additionally, the strength of the income gradient in health varies between age groups. The relatively high health inequalities between income groups in Norway and Finland are already visible in the youngest age groups. The results imply that the socioeconomic gradient in health will arguably not be strongly reduced in the near future as a result of cohort replacement, as has been suggested in previous studies. Health policy interventions may be particularly important five to ten years prior to retirement and in early adulthood.     

What future WHO?

New actors on the international health scene have emerged, challenging WHO's leadership in global health. The role and functions of WHO have been questioned. Changes in financing have eroded the influence of the governing bodies. The Nordic countries, which together provide a considerable share of the total voluntary contributions to WHO, have recently made a number of studies of WHO, pinpointing weaknesses and proposing reforms. A slow reform process is also taking place within WHO. The main conclusions from these studies are analyzed and the areas with the greatest need for reform are studied. This paper presents proposals for the far-reaching reforms needed for WHO to recapture its leadership role in international health.     

Do measures matter? Comparing surface-density-derived and census-tract-derived measures of racial residential segregation

Background  

Racial residential segregation is hypothesized to affect population health by systematically patterning health-relevant exposures and opportunities according to individuals' race or income. Growing interest into the association between residential segregation and health disparities demands more rigorous appraisal of commonly used measures of segregation. Most current studies rely on census tracts as approximations of the local residential environment when calculating segregation indices of either neighborhoods or metropolitan areas. Because census tracts are arbitrary in size and shape, reliance on this geographic scale limits understanding of place-health associations. More flexible, explicitly spatial derivations of traditional segregation indices have been proposed but have not been compared with tract-derived measures in the context of health disparities studies common to social epidemiology, health demography, or medical geography. We compared segregation measured with tract-derived as well as GIS surface-density-derived indices. Measures were compared by region and population size, and segregation measures were linked to birth record to estimate the difference in association between segregation and very preterm birth. Separate analyses focus on metropolitan segregation and on neighborhood segregation.     

Rabies and rabies-related viruses: a modern perspective on an ancient disease

Rabies is a worldwide zoonosis caused by a lyssavirus, with many host species acting as reservoirs for infection. The epidemiology of rabies has changed over recent years, as this disease has been brought under control or eliminated in many terrestrial animal species in Europe and North America. A large number of Lyssavirus variants have now been characterised, and their distribution and animal hosts have become known. However, new lyssaviruses have been isolated from bats, prompting scientists to question the efficacy of the existing human and veterinary vaccines against these new strains. The epidemiology of bat rabies should be fully explored, so that the precise risks to the health of humans and domestic and wild carnivores may be determined and methods of preventing the disease among people who handle bats can be discovered. Rabies is still a significant public health problem, particularly in areas where canine rabies is still endemic, such as countries in Africa and Asia.     

Perinatal mortality rates: adjusting for risk factor profile is essential

Perinatal mortality has long been used as a comparative measure of health and health care across regions, countries and over time. Recently, the validity of the measure has been questioned. Using data from a population-based survey of late fetal losses, stillbirths and infant deaths, the Northern Perinatal Mortality Survey, we demonstrate the potential for inaccuracy of crude measures of perinatal mortality. Such measures are generally not adjusted for characteristics of the population (e.g. birthweight, maternal age, plurality, gender) which are known to affect risk of adverse pregnancy outcome when comparing temporal or geographical trends. We also show the effect of standardising for these factors on the most frequent causes of perinatal death. We recommend the construction of a 'standard birth population' for calculating standardised perinatal mortality rates that would improve direct comparisons between populations.     

Socioeconomic inequalities and low birth weight and perinatal mortality in Rio de Janeiro, Brazil

Socioeconomic inequalities in early infant mortality have been evidenced in Brazil, with a greater mortality risk associated with the mother's socioeconomic status (SES). The aim of this paper is to identify socioeconomic inequalities in relation to low birth weight and perinatal mortality in the City of Rio de Janeiro, Brazil, discussing the appropriateness of the main health inequality indexes proposed in the international literature. As the information source, we use data collected in a survey of approximately 10,000 mothers selected for interview within 48 hours after delivery in public and private hospitals in the city. Using educational level and head of household's income as indicators of SES, as well as population attributable risk and slope index of inequality as health inequality measures, the results show a steep socioeconomic gradient in the proportion of low birth weight, and especially in the perinatal mortality rate. The persistent association between socioeconomic indicators and adverse results in pregnancy indicates (at least partially) the health system's inefficacy in diminishing perinatal health inequalities in Rio de Janeiro.     

Epidemiologische Krebsregistrierung in Deutschland

Although cancer registration has a long tradition in Germany, wide areas remained blank spaces on the map concerning population-based cancer registration. The situation changed completely when a federal law on cancer registration (KRG, 1995-1999) took effect. Now all federal states have established population-based cancer registries on a legal basis. In spite of the uniform model of cancer registration anchored in the KRG, 16 different models have developed in Germany. Completeness of cancer registration was constantly improved over the last several years. In addition to the Saarland cancer registry, further registries can now provide a high grade of registration for all cancer sites. Essential tasks, such as public reporting and support of cancer research, can now be better fulfilled. Even taking the great developments in cancer registration in Germany into consideration, some deficits still continue to exist. These deficits are mostly caused by heterogeneity and missing compatibility of the cancer registry laws of the federal states. After the focus of cancer registration was on developing valid registries,now the focus has to be changed to the usability of cancer registry data. These data can be used e. g. for research on etiology and evaluation of programs on early cancer detection. Scientists in the field of cancer epidemiology, public health, and cancer care are invited to use data of cancer registries for research and evaluation projects intensively.     

Perinatal Distress in Women in Low- and Middle-Income Countries: Allostatic Load as a Framework to Examine the Effect of Perinatal Distress on Preterm Birth and Infant Health

In low- and middle-income countries (LMIC), determinants of women’s and children’s health are complex and differential vulnerability may exist to risk factors of perinatal distress and preterm birth. We examined the contribution of maternal perinatal distress on preterm birth and infant health in terms of infant survival and mother–infant interaction. A critical narrative and interpretive literature review was conducted. Peer-reviewed electronic databases (MEDLINE, Embase, Global Health, CINHAL), grey literature, and reference lists were searched, followed by a consultation exercise. The literature was predominantly from high-income countries. We identify determinants of perinatal distress and explicate changes in the hypothalamic–pituitary–adrenal axis, sympathetic, immune and cardiovascular systems, and behavioral responses resulting in pathophysiological effects. We suggest cultural–neutral composite measures of allostatic mediators (i.e., several biomarkers) of maternal perinatal distress as objective indicators of dysregulation in body systems in pregnant women in LMIC. Understanding causal links of maternal perinatal distress to preterm birth in women in LMIC should be a priority. The roles of allostasis and allostatic load are considered within the context of the health of pregnant women and fetuses/newborns in LMIC with emphasis on identifying objective indicators of the level of perinatal distress and protective factors or processes contributing to resilience while facing toxic stress. We propose a prospective study design with multiple measures across pregnancy and postpartum requiring complex statistical modeling. Building research capacity through partnering researchers in high-income countries and LMIC and reflecting on unique ethical challenges will be important to generating new knowledge in LMIC.     

Register based monitoring shows decreasing socioeconomic differences in Finnish perinatal health

STUDY OBJECTIVE: Several studies on differences in infant outcome by socioeconomic position have been done, but these have usually been based on ad hoc data linkages. The aim of this paper was to investigate whether socioeconomic differences in perinatal health in Finland could be regularly monitored using routinely collected data from one single register. DESIGN AND SETTING: Since October 1990, the Finnish Medical Birth Register (MBR) has included data on maternal occupation. A special computer program that converted the occupation name into an occupational code and into a socioeconomic position was prepared. Perinatal health was measured with five different indicators. The Finnish MBR data for years 1991 to 1999 (n=565 863 newborns) were used in the study. The study period was divided into three, three year periods to study time trends. RESULTS: An occupational code was derived for 95% of women, but it was not possible to define a socioeconomic position for 22% of women, including, for example, students and housewives (the group "Others"). For the rest, the data showed socioeconomic differences in all perinatal health indicators. Maternal smoking explained up to half of the excess risk for adverse perinatal outcome in the lowest socioeconomic group. The socioeconomic differences narrowed during the 1990s: infant outcome improved in the lowest socioeconomic group, but remained at the same level or even deteriorated in other groups. When comparing the lowest group with the highest group, the odds ratios (OR) adjusted for maternal background characteristics at least halved for prematurity (from 1.32 (95% confidence intervals 1.24 to 1.43) in 1991-1993 to 1.16 (1.08 to 1.25) in 1997-1999), for low birth weight (from 1.49 (1.36 to 1.63) to 1.25 (1.17 to 1.40)), and for perinatal mortality (from 1.79 (1.44 to 2.21) to 1.33 (1.07 to 1.66)). CONCLUSIONS: Social inequality in perinatal health outcomes exists in Finland, but seems to have diminished in the 1990s. These data showed that routinely collected birth register data provide a good source for studies on socioeconomic health differences in the perinatal period, but that uncertainty, mainly attributable to the large group of women with difficult to classify socioeconomic status, remains.     

Intergenerational exchange and perinatal risks: a note on interpretation of generational recurrence risks

Population-based data that cover reproductive health outcomes across two complete generations have recently become available in the Nordic countries. Such data enable estimation of recurrence risks from one generation to the next of different conditions such as birth defects or pre-eclampsia. Risks related to a singleton pregnancy involve the contribution of three individuals: the mother, the father and the fetus. A paternal contribution is mainly through the father's contribution of half of the alleles of the fetus. A maternal contribution may occur in three fundamentally different ways. First, the mother provides half of the genomic alleles to the fetus, with contribution of paternal alleles completing the whole genome. Second, the mother provides the fetal environment and possible susceptibility to complications during pregnancy which she may have inherited from her mother. Finally, she provides the fetal mitochondria. Because of these different contributions, recurrence from mother to offspring is fundamentally different from recurrence from father to offspring. How recurrence risks reflect and shape the underlying contributions to overall perinatal risk is illustrated through a review of published data from Norway on gestational age, pre-eclampsia and birth defects.     

Dioxin effects on neonatal and infant thyroid function: routes of perinatal exposure, mechanisms of action and evidence from epidemiology studies

Objectives: Animal experiments suggest that thyroid function alterations in newborns and infants may represent one of the most sensitive markers of toxicity from 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Dioxin can be transferred from the mother to the offspring either in utero or through lactation. It has been suggested that thyroid-hormone alterations produced by dioxin in utero or shortly after birth may underlie long-term effects, such as cognitive-ability and neurodevelopment impairment. In the present review article, we appraise available evidence on the effects of perinatal exposure to dioxin on fetal and infant thyroid function. Methods: We summarized the routes of perinatal dioxin exposure and research results on possible mechanisms of dioxin toxic effects on thyroid function. We performed a systematic review of epidemiology studies conducted on mother–child pairs exposed to background environmental levels to investigate dioxin effects on neonatal and infant thyroid function. Results: Toxicological and mechanistic data indicate that dioxin may impair thyroid function in exposed newborns and infants. Investigations on background-exposed children have not consistently demonstrated an association between perinatal TCDD exposure and thyroid function, although some of the studies suggest that sub-clinical hypothyroidism may be induced by perinatal dioxin exposure within 3 months from birth. Between studies inconsistencies may be related to lab method differences, mixed exposures, and small sample size of the populations evaluated. Conclusion: Epidemiology studies have as yet failed to demonstrate an association between perinatal TCDD exposure and thyroid function alterations in human subjects, although suggestive evidence from animal and in-vitro experimental data is available.     

A short history of pathology registries,with emphasis on cancer registries

In the 1950s, major technical problems for ensuring quality and effectiveness of population based registration of cancer and other conditions had been faced and solved. Nevertheless, the classical epidemiological texts published in the 1960s and the 1970s gave little attention to and showed limited enthusiasm for population-based registries of pathology. The latter, in fact, have been marginal to the dramatic evolution of basic conceptual issues such as study design and causal inference. This perspective may change with the use of registries in order to assess quality of care in a public health perspective. In looking retrospectively, marked changes occurred since the 1960s in distribution between countries and continents of cancer registries to the dataset known as "Cancer Incidence in Five Continents" (where worldwide data from cancer registries of quality converge). The number of countries with cancer registries approximately doubled vs. a fivefold increase in both the number of active cancer registries and the total population served by registration. Nevertheless the increases were concentrated in developed countries whereas in developing countries there was a substantial decrease in registration, attributable to the political and economical situation.     

Epidemiology of epilepsy in developing countries.

Epilepsy is an important health problem in developing countries, where its prevalence can be up to 57 per 1000 population. This article reviews the epidemiology of epilepsy in developing countries in terms of its incidence, prevalence, seizure type, mortality data, and etiological factors. The prevalence of epilepsy is particularly high in Latin America and in several African countries, notably Liberia, Nigeria, and the United Republic of Tanzania. Parasitic infections, particularly neurocysticercosis, are important etiological factors for epilepsy in many of these countries. Other reasons for the high prevalence include intracranial infections of bacterial or viral origin, perinatal brain damage, head injuries, toxic agents, and hereditary factors. Many of these factors are, however, preventable or modifiable, and the introduction of appropriate measures to achieve this could lead to a substantial decrease in the incidence of epilepsy in developing countries.     

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.