Patterns and variations in the relationship between infant mortality and socioeconomic status

Abstract

This study utilizes an ecological approach based on census tracts of residence to examine the relationship between infant mortality and socioeconomic status in metropolitan Ohio at two points in time (1959–61 and 1969–71). The data presented clearly indicate that the infant mortality rate continues to exhibit a pronounced inverse association with a wide variety of socio‐economic variables. Although there were some notable exceptions and/or variations from the general patterns, a basic inverse relationship was generally found to be characteristic of both neonatal and postnatal components of infant mortality, for both males and females, and for both major exogenous and endogenous causes of death. Of all the variables examined, the one factor that emerged as the strongest and most consistent determinant of census tract variations in infant mortality was the proportion of low income families. Thus, the overriding conclusion suggested by this study is that in spite of such things as continued advances in medicine and public health, the expansion of a variety of social programs during the 1960's, and the recent resumption of a downward trend in the overall infant mortality rate, there has been little if any progress in achieving more equitable life chances for the economically deprived segments of our population.     

Racial differences in the relationship between infant mortality and socioeconomic status

This study presents an ecological analysis of the relationship between infant mortality and economic status by race in metropolitan Ohio, using census data on mother's residence and economic status determined by the percentage of low-income families living in each area. The analysis updates previous studies as white-non-white comparisons for total infant mortality are examined for the US censuses of 1960, 1970, 1980, 1990 and 2000; and more detailed period- and broad cause-specific rates are presented for 2000. A pronounced inverse association is consistently found between income status and infant mortality for whites, while for non-whites this pattern first emerges in 1979-81, disappears during the 1980s and then returns more strongly during the 1990s. Similarly, the 2000 data reveal a consistent inverse pattern between income status and infant mortality for white and non-white neonatal and postneonatal death rates, as well as exogenous cause-specific death rates. It is concluded that low-income whites and non-whites have infant mortality rates substantially higher than the overall rate for the population. Policy implications are discussed.     

The relationship between socioeconomic status and infant mortality in metropolitan Ohio, 1999–2001

Abstract

Empirical evidence has consistently documented the direct relationship between infant mortality and socioeconomic inequality in the United States and numerous other countries. While the majority of these studies reveal an inverse relationship between socioeconomic level and infant mortality, not even this finding is free from disagreement. Furthermore, the specific nature and magnitude of this relationship has varied over time.

This study will examine the relationship between socioeconomic status and infant mortality in metropolitan Ohio by using birth and infant death data centered on the 2000 Census. The analyses presented herein will describe and analyze the relationship between infant mortality and socioeconomic status in metropolitan Ohio in the year 2000. The key finding is that in spite of remarkable declines in infant mortality during the past several decades, most notably in neonatal mortality, there continues to be a pronounced inverse association between the infant death rate and the economic status of a population.     

Determinants of infant and early childhood mortality in Cameroon: The role of socioeconomic factors,housing characteristics,and immunization status

Abstract

This study examines factors impinging on the survival of children in Cameroon using longitudinal data collected by the United Nations Demographic Training and Research Institute of Yaounde, Cameroon. It deals especially with the role of socioeconomic factors (mother's education, employment, marital status, ethnicity, and household income), housing characteristics (construction materials, power source, source of water supply, extent of crowding), and immunization status on infant and child mortality. Two‐state parametric and nonparametric hazards models for the risk of death at any time within the course of the study are used, with and without accounting for unmeasured heterogeneity. Overall, overcrowding has robust deleterious effects on infant and child survival. As regards the effects of socioeconomic variables, the robustness of the effects of household income and ethnic differentials are unchanged, even after controlling for unmeasured heterogeneity; the deleterious effects of marital status are also apparent, but these effects are largely explained by unmeasured covariates. The data also suggest that the protective effects of full immunization status are robust and not contaminated by confounding factors, at least in the first 16 months of life. These findings provide solid ground to support immunization programs and efforts as a means to reduce significantly infant and child mortality.     

Sudden infant death syndrome and the age‐cause proxy relationship in infancy

Abstract

Evidence from a longitudinal study of the relationship between socioeconomic status and infant mortality in metropolitan Ohio is presented in an effort to throw additional light on the continuing debate over the validity of the age‐cause proxy relationship in infancy. The results indicate that while there is a fairly strong and consistent association between neonatal mortality and endogenous causes of death that is little affected by the classification of Sudden Infant Death Syndrome, the nature of the association between postneonatal mortality and exogenous causes of death varies from weak to moderate depending upon where this cause is included. Additional evidence pertaining to the role of SIDS in contributing to the long‐standing inverse association between infant mortality and socioeconomic status is presented, thus further emphasizing the need for continued research to clarify the etiologic mechanisms of this poorly understood condition.     

A methodological note on the relationship between infant mortality and socioeconomic status with evidence from San Antonio, Texas.

A number of previous studies have concluded from social area analyses of medium-size cities that there is no longer a significant correlation between socioeconomic status (SES) and infant mortality in the U.S. To determine if these findings were an artifact of too small samples, the total, neonatal, and postneonatal infant mortality rates were analyzed for 115 census tracts of San Antonio, Texas. The SES of each tract was measured by a score reflecting equally the variables of income, education, and occupation, and allowed assignment of the tracts to 1 of 4 socioeconomic rankings. All 3 infant mortality rates rose as SES decreased, with the most marked relationship being between SES and postneonatal rates. It was also found that of the 3 variables used to measure SES, income bore the strongest relationship to infant mortality. In general it should be noted that social area analysis of infant mortality is limited by the extreme reductions of sample size when additional variables are induced.     

Changing determinants of infant and child mortality: on the basis of the Korean experience, 1955-73

Data from the 1974 Korean National Fertility Survey were analyzed to learn more about the main determinants of infant and child mortality in the course of mortality decline and how they change. In the Korean survey, about 5000 eligible women were selected for the individual survey and the sample design aimed at a self-weighting nationally representative and probability sample. Preliminary analysis showed clear mortality differentials between different socioeconomic levels and between demographic subgroups in infant and child mortality during the period 1955-73 in Korea. To examine the net effect of each variable on mortality, the logit-linear model was used. A table shows the probability level of 4 variables -- maternal age, birth order, mother's education, and number of rooms used by household -- in Korea, when the effects of others were controlled. In the urban areas, only the socioeconomic factors were the main determinants of infant mortality on all the birth cohorts. Mother's education and number of rooms used strongly affected infant mortality in the 1955-59 and 1960-64 birth cohorts, but the effects became weaker in the 1965-69 and 1970-73 birth cohorts, and their statistical significance was reduced. In the rural areas, the effects of 3 variables -- the exception being number of rooms used -- on infant mortality were statistically significant. It is concluded that the main determinants of infant mortality in urban areas were socioeconomic factors. The main determinants of infant mortality in the rural areas were demographic in the earlier birth cohorts, but in the recent birth cohorts mother's education, a socioeconomic factor, became the main determinant while the effects of demographic variables became weaker and finally disappeared. The change in the determinants of child mortality appears to be the reverse of that for infant mortality. Prior to the introduction of the national development program, in the rural areas mother's education was the main determinant of child mortality (rural 1955-59 cohort), but with the socioeconomic development the determinants changed to give dominance to demographic factors (urban 1955-59) cohort and, in the recent period, even the effects of demographic factors on child mortality became weaker (urban 1960-69 cohort). When the differences in living status by maternal age were weaker and the competition among siblings less because of small family size, only the socioeconomic variables remained as main determinants affecting child mortality.     

Heredity counseling

Abstract

An ecological analysis of infant mortality rates is conducted using data on Texas counties for the years 1968–72. It is found that when counties along the Texas‐Mexico border (which have unreasonably low infant death rates and which are economically less advantaged than the remainder of the counties) are excluded from the analysis, the associations between socioeconomic status variables and infant mortality rates improve considerably. A significant negative correlation between neonatal mortality and per cent Spanish surname is retained and does not disappear when the effects of other relevant variables (per cent Negro, per cent urban, and per cent below poverty) are controlled using partial correlation and regression analysis. Possible explanations for this unexpected finding are suggested, and implications for further research are discussed.     

The relationship between socioeconomic status and infant mortality in metropolitan Ohio, 1999-2001

Empirical evidence has consistently documented the direct relationship between infant mortality and socioeconomic inequality in the United States and numerous other countries. While the majority of these studies reveal an inverse relationship between socioeconomic level and infant mortality, not even this finding is free from disagreement. Furthermore, the specific nature and magnitude of this relationship has varied over time. This study will examine the relationship between socioeconomic status and infant mortality in metropolitan Ohio by using birth and infant death data centered on the 2000 Census. The analyses presented herein will describe and analyze the relationship between infant mortality and socioeconomic status in metropolitan Ohio in the year 2000. The key finding is that in spite of remarkable declines in infant mortality during the past several decades, most notably in neonatal mortality, there continues to be a pronounced inverse association between the infant death rate and the economic status of a population.     

Teenage fertility, socioeconomic status and infant mortality

This paper examines the relationship between infant mortality and a complex measure of socioeconomic status for evidence of diminution. In data on counties in the US with a minimum of 20 infant deaths over the 5-year period 1971-75, no evidence of a declining relationship between socioeconomic status and infant mortality was found. Both level of community affluence and racial composition of the population exerted direct effects on levels of infant deaths. In addition, both socioeconomic status and racial composition exhibited indirect effects which operated through teenage childbearing. When total infant mortality was subdivided, teenage fertility serves as a mediating variable in the link between socioeconomic status and neonatal mortality, but not for the postneonatal components. Given the nearly equivalent total effect of socioeconomic status on infant mortality, it is concluded that the classic division into neonatal (supposedly a function of biological and genetic agents) and postneonatal (traditionally attributed to social and environmental agents), may be too crude to allow the contemporary effects of the socioenvironmental milieu to be evaluated effectively.     

Infant mortality in Zambia: socioeconomic and demographic correlates

Trends in infant mortality in Zambia suggest a reversal of the decline experienced between the 1960s and the late 1970s. From a high of about 140, infant mortality rate declined to about 90 in the late 1970s only to rise again to 100 by 1996. Data on 5,600 births born between 1987 and 1992, and 6,630 births between 1991 and 1996 from the Zambian DHS are analyzed to identify socioeconomic and demographic correlates of infant mortality. Demographic factors such as small size at birth and short birth intervals are associated with higher neonatal mortality. In the post-neonatal period, urban children from poorer households had the highest mortality between 1991-1996. Also, differences in infant mortality rates between provinces narrowed. Children born in the most developed province of Lusaka had as high of risk of dying as those from Luapula, a province with a history of extremely high mortality rates in Zambia.     

The age-cause proxy relationship in infant mortality

Data presented in this brief note show that one of the consequences of recent gains in the control of neonatal mortality has been an increase in the frequency of endogenous causes of death in the postneonatal period. Several conclusions are readily apparent from the data presented here. 1st, with respect to total infant mortality, the vast majority of the deaths under 1 year of age today are caused by the endogenous conditions that are most closely associated with the physiological processes of gestation and births. 2nd, both the exogenous and endogenous cause-specific death rates are inversely associated with family income status. The strength of the relationship, as measured by the difference between the death rates of the highest and lowest income areas, is much greater for the environmentally related exogenous causes. Further, there is an obvious tendency for the exogenous causes to account for an increasing proportion of total deaths as income status decreases. While these data support research findings that challenge the validity of the traditional age/cause of death proxy relationship in infancy, they suggest that recommendations for enhancing the neonatal/endogenous relationship by shortening the neonatal period may be premature.     

Reproductive and socioeconomic determinants of child survival: Confounded,interactive, and age‐dependent effects

Abstract

Studies of infant and child mortality have evolved to distinguish between two sets of explanatory variables—factors related to reproductive or maternal characteristics and socioeconomic factors, generally described as characteristics of the family or household. Almost all multivariate analyses include variables from each of these two sets, but there has been little consideration of the relationship between them. We examine how these two sets of variables jointly affect mortality. We test first for confounded effects by examining socioeconomic effects while excluding and then including reproductive variables in nested multivariate models. Next, we look for age‐dependent effects among the explanatory variables and find that reproductive and socioeconomic factors affect mortality at differing ages of children. Finally, we examine interactive effects of the two sets of variables. We conclude that the higher mortality observed among the low status groups is not a result of greater concentration of poor reproductive patterns in those groups. Instead, higher status groups probably have more resources available for combating the negative effects of the same high‐risk reproductive patterns.     

Socioeconomic status and infant mortality among Hispanics in a southwestern city

Abstract

From data on census tract groupings from Corpus Christi, Texas, for 1979–83, this study shows that, unlike the inverse infant‐mortality‐socioeconomic‐status association observed for Anglos, no such association exists for the Spanish surname population. This finding is discussed in terms of recent research suggesting that the Spanish surname population of the Southwest has lower infant death rates than expected from its generally lower socioeconomic status.     

Hereditary susceptibility in rheumatic fever

Abstract

The authors criticize past studies for concluding that the relationship between socio‐economic status and infant mortality has declined in modern industrial societies to the degree that it is almost nonexistent. Such studies computed infant death rates utilizing small numbers of births and deaths, resulting in unreliable rates. In this study, social area analysis is employed in a fairly large city with vital data from the early 1970's. The findings indicate a rather strong relationship still exists between SES and infant mortality. Limitations of social area analysis are discussed, and suggestions for future research are given.     

The fall and rise of US inequities in premature mortality: 1960-2002

Background

Debates exist as to whether, as overall population health improves, the absolute and relative magnitude of income- and race/ethnicity-related health disparities necessarily increase—or derease. We accordingly decided to test the hypothesis that health inequities widen—or shrink—in a context of declining mortality rates, by examining annual US mortality data over a 42 year period.

Methods and Findings

Using US county mortality data from 1960–2002 and county median family income data from the 1960–2000 decennial censuses, we analyzed the rates of premature mortality (deaths among persons under age 65) and infant death (deaths among persons under age 1) by quintiles of county median family income weighted by county population size. Between 1960 and 2002, as US premature mortality and infant death rates declined in all county income quintiles, socioeconomic and racial/ethnic inequities in premature mortality and infant death (both relative and absolute) shrank between 1966 and 1980, especially for US populations of color; thereafter, the relative health inequities widened and the absolute differences barely changed in magnitude. Had all persons experienced the same yearly age-specific premature mortality rates as the white population living in the highest income quintile, between 1960 and 2002, 14% of the white premature deaths and 30% of the premature deaths among populations of color would not have occurred.

Conclusions

The observed trends refute arguments that health inequities inevitably widen—or shrink—as population health improves. Instead, the magnitude of health inequalities can fall or rise; it is our job to understand why.     

Socioeconomic development,medical care,and nutrition as determinants of infant mortality in less‐developed countries

Abstract

Using data for sixty less‐developed countries, we constructed a causal model in which medical care, nutrition, status of women, and socioeconomic development are examined as determinants of infant mortality. Social and economic development are treated as exogenous variables; medical care, nutrition, and status of women are viewed as variables endogenous to the model. The model is tested by maximum likelihood methods. Results indicate that good nutrition and the presence of informally trained health care personnel, i.e., midwives, are more significantly related to low rates of infant mortality than are the employment status of women and the presence of formally trained health care personnel such as physicians and nurses. The general level of social and economic development conditions these relationships.     

Birthweight‐specific infant mortality risks for native Americans and whites,United States, 1960 and 1984

Abstract

We used NCHS natality and linked‐birth/death certificate tapes to compare birthweight‐specific neonatal and postneonatal mortality risks for Native Americans and whites in 1960 and in 1984. The birthweight distributions for the two groups were similar both years. Native American neonatal mortality risk dropped from 20.2 in 1960 to 5.2 in 1984, and the relative risk for Native Americans with respect to whites fell from 1.31 in 1960 to a nonsignificant difference in 1984. Postneonatal mortality risks for Native Americans fell from 27.5 in 1960 to 6.2 in 1984, with a drop in the relative risk from 5.2 to 2.1. Although the relative improvements for Native Americans were highest in postneonatal survival, Native Americans still had over twice the level of white postneonatal mortality. Birthweight was positively associated with survival for both groups, but the odds of Native American neonatal death were affected less by low and very low birthweights. For both groups, improvements in neonatal mortality were highest at the lower birthweights, while the gains in postneonatal survival benefitted normal and high birthweight infants most.     

Relationships between pregnancy spacing,sex of infants,maternal age,and birth order,and neonatal and post‐neonatal mortality in Bangladesh

Abstract

The relationships between length of the interpregnancy interval, outcome of the pregnancy preceding the interval, sex of the infants, pregnancy order, maternal age, and maternal history of previous child deaths and neonatal and postneonatal mortality were explored in a rural Bangladeshi population using a multiple regression analysis. Specific interactions between the interpregnancy interval, outcome of the pregnancy preceding the interval, sex of the infants, and history of previous child deaths were examined. An inverse relationship was observed between postneonatal mortality and the length of the interpregnancy interval when the pregnancy preceding the interval was a surviving infant. No such trend was observed for neonatal mortality. Post‐neonatal mortality rates among children whose mothers had experienced two or more previous child deaths were essentially the same as that for infants whose mothers had experienced 0–1 child deaths when the interpregnancy intervals were more than 24 months. Although female infants have a lower neonatal mortality than male infants, the neonatal mortality rate for female infants conceived less than twelve months following a male infant birth was higher than for a male infant conceived less than twelve months following another male infant birth. Post‐neonatal mortality is consistently higher for female compared to male infants in all interval categories.     

Infant and child mortality in Bangladesh

Socioeconomic differences and trends in infant and child mortality in Bangladesh are examined using data from the 1975 World Fertility Survey and 1979 Contraceptive Prevalence Survery. There is evidence of some recent decline in infant mortality and child mortality. Logit analysis of infant and child mortality indicates that sociodemographic variables such as mother's education, recent period, or higher birth orders, has significant independent effects upon the reduction of infant and child mortality. Other variables such as fetal loss, father's education, or land ownership had no consistent significant effect. On the other hand the effect of urban residence on infant and child mortality was positive after the control of sociodemographic variables. Mere concentration on the supply of modern medical services may bring limited returns unless they are reinforced by appropriate social changes, in particular those affecting the socioeconomic status of women. Educated mothers are likely to belong to higher income households, have better knowledge of how to care for children, and can bring more resources to the care of a sick child.