Racial differences in infant mortality by cause of death: The impact of birth weight and maternal age

This research examines racial disparities in infant mortality, overall and separately according to cause of death. Using linked birth and death records for the 1975 cohort of live births in Florida, racial differences are initially described and then explained statistically as a product of the distribution of births by birth weight and maternal age. The impact of birth weight is more pronounced than is the effect of maternal age. The analysis suggests the potential utility of examining infant mortality separately by cause of death. Based on the findings, we argue for systematic research focused on factors affecting birth weight.     

The impact of childhood mortality on Fertility in six rural Thanas of Bangladesh

In this article, we examine the relationship between child mortality and subsequent fertility using prospective longitudinal data on births and childhood deaths occurring to nearly 8000 Bangladeshi mothers observed over the 1982-1993 period, a time of rapid fertility decline. Generalized hazard-regression analyses are employed to assess the effect of infant and child mortality on the hazard of conception, with controls for birth order and maternal age and educational attainment. Results show that childhood mortality reduces the time to subsequent conception if the death occurs within a given interval, representing the combined effect of biological and volitional replacement. The time to conception is also reduced if a childhood death occurs during a prior birth interval, a finding that signifies an effect of volitional replacement of the child that died. Moreover, mortality effects in prior birth intervals are consistent with hypothesized insurance (or hoarding) effects. Interaction of replacement with elapsed time suggests that the volitional impact of child mortality increases as the demographic transition progresses. This volitional effect interacts with sex of index child. Investigation of higher-order interactions suggests that this gender-replacement effect has not changed over time.     

The impact of class,education, and health care on infant mortality in a developing society: The case of rural Thailand

Demographic and social factors affecting infant mortality in rural northern Thailand are examined using log-linear modifiedmultiple regression models and data drawn from a representative sample of married couples in Chiang Mai and Chiang Rai provinces. Demographic factors do not account for the effects of variations in parental ability or willingness to provide adequate infant care. The final model estimated incorporated both these social dimensions of child care. Parental ability, measured by father’s social class, mother’s health information, and local community development levels, continued to have significant independent effects upon infant survival. Parental willingness, measured by parent’s beliefs about intergenerational wealth transfers, no longer had a significant effect net of other social variables, but infant survival was still affected by whether both parents wanted a birth.     

Erosion of Advantage: Decomposing Differences in Infant Mortality Rates Among Older Non-Hispanic White and Mexican-Origin Mothers

We build on findings from recent research showing an erosion of infant survival advantage in the Mexican-origin population relative to non-Hispanic whites at older maternal ages, with patterns that differ by nativity. This runs counter to the well-documented Hispanic infant mortality paradox and suggests that weathering and/or other negative health selection mechanisms may contribute to increasing disadvantage at older maternal ages. Using the National Center for Health Statistics (NCHS) cohort-linked birth and infant death files, we decompose the difference in Mexican-origin non-Hispanic white infant mortality at older maternal ages to better understand the contribution of selected medical and social risk factors to components of the difference. We find differences in the distribution and effects of risk factors across the three populations of interest. The infant mortality rate (IMR) gap between Mexican-origin women and non-Hispanic whites can be attributed to numerous offsetting factors, with inadequate prenatal care standing out as a major contributor to the IMR difference. Equalizing access to and utilization of prenatal care may provide one possible route to closing the IMR gap at older maternal ages.     

Direct and indirect effects on infant mortality in a high-fertility US population

This article examines the direct and indirect effects of social and demographic measures on infant mortality using data from a church directory of the Old Order Amish of the Lancaster, PA, Settlement. The sample includes all infant deaths and a simple random sample of survivors (total n=2013). The results reveal that the death of the immediately prior sibling directly increases the risk of infant death nearly 30%, net of other factors. Also, the risk of mortality in the first year increases as birth order increases, particularly at the highest orders (8–17 prior sibs). Infants of the youngest mothers (age 13) are nearly 10% more likely to die in the first year of life than are infants of mothers age 24, nearly all of which is indirect via parity, prior sib death and birth interval. Further analysis shows that families adapting more rapidly to external community pressures face a higher risk of infant death than families living in more stable areas. These relationships emerge even in this homogeneous population with a relatively high standard of living and a traditional lifestyle, Implications are that indirect effects should be included in research on teen pregnancy and infant survival, and might be especially important for studies in transitional geographic areas.An earlier version of this paper was presented at the 1993 meetings of Population Association of America, Cincinnati.     

Changes in fertility patterns can improve child survival in Southeast Asia

This analysis of 1988 Philippine Demographic Survey data provides information on the direct and indirect effects of several major determinants of childhood mortality in the Philippines. Data are compared to rates in Indonesia and Thailand. The odds of infant mortality in the Philippines are reduced by 39% by spacing children more than two years apart. This finding is significant because infant mortality rates have not declined over the past 20 years. Child survival is related to the number of children in the family, the spacing of the children, the mother's age and education, and the risks of malnutrition and infection. Directs effects on child survival are related to infant survival status of the preceding child and the length of the preceding birth interval, while key indirect or background variables are maternal age and education, birth order, and place of residence. The two-stage causation model is tested with data on 13,716 ever married women aged 15-49 years and 20,015 index children born between January 1977 and February 1987. Results in the Philippine confirm that maternal age, birth order, mortality of the previous child, and maternal education are directly related to birth interval, while mortality of the previous child, birth order, and maternal educational status are directly related to infant mortality. Thailand, Indonesia, and the Philippines all show similar explanatory factors that directly influence infant mortality. The survival status of the preceding child is the most important predictor in all three countries and is particularly strong in Thailand. This factor acts through the limited time interval for rejuvenation of mother's body, nutritional deficiencies, and transmission of infectious disease among siblings. The conclusion is that poor environmental conditions increase vulnerability to illness and death. There are 133% greater odds of having a short birth interval among young urban women than among older rural women. There is a 29% increase in odds for second parity births compared to third or higher order parities. Maternal education is a strong predictor of infant survival only in the Philippines and Indonesia. Adolescent pregnancy is a risk only in Indonesia. Socioeconomic factors are not as important as birth interval, birth order, and maternal education in determining survival status.     

Fertility decline in a US population favoring large families: A hazard-model analysis of the effect of sib death on Amish fertility

This paper uses proportional hazards techniques and population data from a directory of the Old Order Amish of the Lancaster, PA settlement. It examines the effect of death of the immediately prior sibling on the risk of childbearing for up to 11 children. Prior research typically has pooled data for maternal cohorts. In contrast, separate models are estimated for each maternal cohort. The results are based on all reported first marriages of Amish women born between 1884–1973 (N = 4066). Hazard models run separately for children of each birth order reveal that net of maternal age and length of the prior birth interval (and other statistical and design controls), the death of the prior sib significantly increases the risk of a subsequent birth for the lower birth orders. Separate models by maternal cohort show that sib death increases the risk primarily for later cohorts. The pattern of effects from child mortality and other variables suggests changes in fertility behavior among the Amish, who have strong, traditional norms opposing contraception and favoring large families.     

Demographic and Economic Correlates of Development as Measured by Energy Consumption

Per capita consumption of energy in 112 world areas was related to a series of economic and demographic variables. Linear associations were found for four economic variables, and a curvilinear association in the form of a J curve for four demographic variables. It was found that the exponential distribution y = e(-X) for the curves for the demographic variables (crude birth rate, infant mortality rate, percent of deaths from contagious and infectious diseases, and life expectancy). By using a table of exponential functions, one can determine values for the distribution of these variables and the crude death rate for any desired level of energy consumption.     

Rural–Urban Migration and Cross-National Variation in Infant Mortality in Less Developed Countries

The relationship between migration and child health in individual countries is well known, but the cross-national variation in this relationship is largely untested. Using Demographic and Health Survey (DHS) data from 52 medium and low income countries, this study examines the effect of rural–urban migration on infant mortality and whether its effect varies cross-nationally. A secondary objective is to determine whether there is a relationship between the time a child is born in the migration process and infant mortality. Hypotheses are developed on the basis of competing theories on the relationship between migration and health. There are modest, but significant cross-national effects of rural–urban migration on infant mortality, which were better revealed in the presence of family- and child-level variables. The results also show that the unadjusted effects of rural–urban migration are quite substantial, but were largely accounted for by family- and child-level factors including education, socioeconomic status (SES), marital status, birth order, maternal age at child’s birth, and inter-births intervals. The results largely point to a selection process, which is further confirmed by results showing that the hazards of infant death increase with length of urban residence. Programs that target increasing maternal education, improving household SES, and lengthening interbirth intervals would therefore greatly benefit child survival in less developed countries.     

Geographic Ancestry and Cause-specific Mortality in a National Population

There are marked differentials in mortality risks across regions in Finland. No exhaustive explanation to this variation has been provided, however. The aim of this paper is to analyse how geographic ancestry, as proxied by persons’ birth region and population group, interrelates with cause-specific mortality risks. Focusing on people aged between their mid-thirties and late-forties, we use longitudinal population register data that offer opportunities to account for variables that represent both persons’ social background and their own social status at young adult age. Results of Cox proportional hazard models say that these variables have substantial effects on mortality of different causes, but only a marginal impact on the variation in death rates by birth region and population group. The geographic mortality pattern is found to be specifically prominent for causes of death that are fairly unrelated to persons’ lifestyles. Our findings suggest that genetic predisposal as expressed in terms of geographic ancestry might play a relevant role in understanding mortality variation within the population of Finland.     

A comment on ‘social and economic factors in Hong Kong's fertility decline’ by Sui-Ying Wat and R. W. Hodge

The recent article by Wat and Hodge appears to make incorrect inferences about the relation of certain social and economic indicators (infant mortality, employment opportunities for women, and education) to Hong Kong's fertility decline, based on a multiple regression of these variables to the crude birth rate of Hong Kong for 1951–1967. Such modernization measures probably have at least a long-run causal relation to fertility decline. It is also possible that the family planning programme ofHong Kong may have added little to the effects, as the authors suggest. However, I do not believe that their multiple regression analysis establishes these conclusions.     

A comment on 'social and economic factors in Hong Kong's fertility decline' by Sui-Ying Wat and R. W. Hodge

Abstract The recent article by Wat and Hodge appears to make incorrect inferences about the relation of certain social and economic indicators (infant mortality, employment opportunities for women, and education) to Hong Kong's fertility decline, based on a multiple regression of these variables to the crude birth rate of Hong Kong for 1951-1967. Such modernization measures probably have at least a long-run causal relation to fertility decline. It is also possible that the family planning programme ofHong Kong may have added little to the effects, as the authors suggest. However, I do not believe that their multiple regression analysis establishes these conclusions.     

Demographic models of birth outcomes and infant mortality: An alternative measurement approach

Most demographic studies use 2,500 grams of birth weight and 37 weeks of gestation as cutpoints for evaluating the effects of adverse birth outcomes on infant mortality. We propose an alternative strategy, which relies on continuous measures of birth outcomes, identifies an optimal combination of birth weight and gestational age for infant survival, and estimates the effects of adverse birth outcomes in terms of their departure from this "optimal point." We illustrate the advantages of this approach by estimating a logistic model using data from the 1989-1991 NCHS linked birth/infant death files. Finally, we discuss future applications and methodological issues to be resolved in subsequent research.     

Maternal Education, Birth Weight, and Infant Mortality in the United States

This research determines whether the observed decline in infant mortality with socioeconomic level, operationalized as maternal education (dichotomized as college or more, versus high school or less), is due to its “indirect” effect (operating through birth weight) and/or to its “direct” effect (independent of birth weight). The data used are the 2001 U.S. national African American, Mexican American, and European American birth cohorts by sex. The analysis explores the birth outcomes of infants undergoing normal and compromised fetal development separately by using covariate density defined mixture of logistic regressions (CDDmlr). Among normal births, mean birth weight increases significantly (by 27–108 g) with higher maternal education. Mortality declines significantly (by a factor of 0.40–0.96) through the direct effect of education. The indirect effect of education among normal births is small but significant in three cohorts. Furthermore, the indirect effect of maternal education tends to increase mortality despite improved birth weight. Among compromised births, education has small and inconsistent effects on birth weight and infant mortality. Overall, our results are consistent with the view that the decrease in infant death by socioeconomic level is not mediated by improved birth weight. Interventions targeting birth weight may not result in lower infant mortality.     

Absolute Change in Cause-Specific Infant Mortality for Blacks and Whites in the US: 1983–2002

This paper examines absolute change in infant mortality from 5 leading causes of death for whites and blacks over a 20 year period. Change in infant mortality varies by cause, race, and birth weight. Absolute decline in mortality from respiratory distress syndrome (RDS) and sudden infant death syndrome (SIDS) in the overall study population has been more rapid for black infants during the period after specific technological innovations were approved and behavioral practices were recommended for these conditions. For low birth weight infants, blacks experienced greater decline in mortality from SIDS and whites experienced greater decline in RDS mortality. Despite remarkable declines in mortality from these causes, relative racial disparities have increased over this time period. For the overall study population, blacks and whites experienced similar rates of mortality decline from congenital anomalies. Mortality decline from this cause among low birth weight infants occurred at a faster pace for whites. Mortality from causes for which no specific innovations were developed increased for blacks but remained relatively constant for whites. An analysis of absolute change complements the relative disparities approach by revealing the dynamics of change, thus providing a more complete understanding of changing racial disparities in infant mortality.     

从"五普"地市数据看生育政策对出生性别比和婴幼儿死亡率性别比的影响

以"五普"数据为基础,分析全国"地市"的出生性别比、婴儿死亡率性别比与生育政策的关系.本文的分析表明实行"第1个孩子为女孩,间隔几年允许生第2个孩子"生育政策的人口比例越高的地区,出生性别比和婴儿死亡性别比失常越严重;实行较为宽松生育政策的地区比较接近正常.实行较为宽松的生育政策有利于解决目前出生性别比严重失常和女婴死亡严重偏高的问题.     

Ethnic and Birth Weight Differences in Cause-Specific Infant Mortality

This article examines ethnic differences in cause-specific infant mortality, using linked birth and infant death records from a cohort of New Mexican singleton infants, 1980-1983. The research, which applies log-linear analysis, focuses on the combined influences of ethnicity, birth weight, maternal age, and plurality on birth outcomes--that is, on infant survival and deaths due to perinatal, congenital, and respiratory diseases and to sudden infant death syndrome. The results confirm the pronounced impact of birth weight on infant mortality and identify similarities and differences among Anglo, Hispanic, and American Indian babies with respect to cause-specific infant mortality.     

The effect of child mortality experience on subsequent fertility: in Pakistan and Bangladesh

Summary This paper presents an empirical analysis of the effects, behavioural and biological, of child mortality experience on subsequent fertility in two South Asian Islamic nations. Data for the investigation came from retrospective pregnancy histories of 2,910 currently married women interviewed in the Pakistan National Impact Survey (1968-69) and from longitudinal vital registration data (1966-2070) of 5,236 women residing in a rural area of Bangladesh collected by the Cholera Research Laboratory. The aim of this study was to assess the importance of the child-replacement motivational response to child death experience after biological effects have been controlled adequately. A common approach employed previously has been to examine cumulative fertility according to child death experience. In Pakistan and Bangladesh, a consistently positive relationship was demonstrated between the number of children ever born and the number of child deaths. This method, however, did not exclude the inverse relationship, the influence of fertility on mortality, nor did it dissect out behavioural from biological effects. Utilizing a measure of subsequent fertility, live-birth-to-live-birth intervals, the study further illustrated another common pitfall. Since the risk of infant death, which leads to shorter birth intervals, is associated with the mother's reproductive history, women with child mortality experience are more likely to experience shorter intervals because of the biological effect of subsequent infant death. Behavioural influences may, therefore, be observed by considering only those birth intervals in which the first-born child survives to the end of the interval. With these limitations controlled, very few, if any, behavioural influences were noted in the Pakistan and Bangladesh data. Median birth intervals in Pakistan varied between 35-43 and 41-42 months, increasing with parity. Within each parity group, no consistent difference was observed between women with and without previous child loss. In Bangladesh, the median birth interval for all women with a surviving infant was 37-2 months. This was shortened to 24-31 months by an infant death. When intervals with infant deaths were excluded, little or no behavioural influence was detected among women of the same parity, but with varying levels of previous child loss. Even without behavioural effects, elimination of infant mortality in Bangladesh would reduce fertility by prolonging the average period of post-partum sterility. In the Bangladesh setting, however, the size of the effect was only about four per cent. This modest effect, more-over, was counterbalanced by an overall increase of net reproduction by seven per cent due to better survivorship of infants.     

Infant death clustering in families: magnitude, causes, and the influence of better health services, Bangladesh 1982-2005

This analysis of infant mortality in Bangladesh focuses on explaining death clustering within families, using prospective data from a rural region in Bangladesh, split into areas with and without extensive health services (the area covered by the International Centre for Diarrhoeal Disease Research and the comparison area, respectively). The modelling framework distinguishes between two explanations of death clustering: (observed and unobserved) heterogeneity across families and a causal 'scarring' effect of the death of one infant on the survival chances of the next to be born. Keeping observed and unobserved characteristics constant, we find scarring in the comparison area only. There the likelihood of infant death is about 29 per cent greater if the previous sibling died in infancy than otherwise. This effect mainly works through birth intervals: infant deaths are followed by shorter birth intervals, which increases the risk of infant death for the next child.     

The linked survival prospects of siblings: evidence for the Indian states

This paper reports an analysis of micro-data for India that shows a high correlation in infant mortality among siblings. In 13 of 15 states, we identify a causal effect of infant death on the risk of infant death of the subsequent sibling (a scarring effect), after controlling for mother-level heterogeneity. The scarring effects are large, the only other covariate with a similarly large effect being mother's (secondary or higher) education. The two states in which evidence of scarring is weak are Punjab, the richest, and Kerala, the socially most progressive. The size of the scarring effect depends upon the sex of the previous child in three states, in a direction consistent with son-preference. Evidence of scarring implies that policies targeted at reducing infant mortality will have social multiplier effects by helping avoid the death of subsequent siblings. Comparison of other covariate effects across the states offers some interesting new insights.