The cocos-keeling islands: A demographic laboratory

The Cocos Islands, which are situated in the Indian Ocean approximately halfway between Colombo and Fremantle, were first peopled early in the nineteenth century and were gradually developed as a very isolated coconut plantation with a labour force consisting partly of persons of Malay stock descended from the original group of settlers and partly of Bantamese contract labourers from Java. As the Cocos-born population increased in size, the dependence on contract labour decreased and, before the end of the century, all immigration ceased. The 1947 Malay population of the islands was about 1,800.

The islands are fascinating from a demographer's point of view because there was a virtually complete registration of live births, deaths and marriages and a partial registration of stillbirths. With these registration records it was possible to construct the life history of every individual from birth, through infancy and childhood to marriage, and thence through fatherhood or motherhood to death.

The picture revealed by an analysis of these records is that of a population with very high fertility and with mortality at a high level before the first World war and at a medium level after that war. Crude birth rates varied between 50 and 60 per thousand population during the period 1888 to 1947. Crude death rates were between 30 and 40 per thousand population until 1912 but under 2.0 per thousand population after 1918.

Most Cocos girls married before reaching the age of 20 and there were an average of between eight and nine live births per woman living through the childbearing period. There was a steady decline in the average number of live births with advancing age at marriage from age 16 onwards. A significantly high proportion of those dying in the middle of the childbearing period had never married, but the fertility of those marrying at an early age (14, 15 and 16) and dying before reaching the age of 36 was slightly higher than that of those who married at a similar age and survived. Women who survived to the age of 55 were of higher fertility than those who died between the ages of 40 and 55. An analysis of birth intervals revealed significant differences (a) between birth intervals after a stillbirth or after a live birth in which the child died in early infancy, and birth intervals after a live birth in which the offspring survived for longer than 0.4 years, and (b) between the interval from first to second birth and the subsequent birth intervals. There was a difference of almost exactly a year between the average birth interval after a stillbirth or live birth ending in a neo-natal death and the average birth interval after the birth of a child surviving to age 2; there was a similar difference of a year between corresponding median birth intervals.

From 1888 to 1912 infant mortality was well above 300 per thousand. After 1918 infant mortality averaged rather under 100 infant deaths per 1,000 live births. The reduction in infant mortality rates was accompanied by an increase in the mortality of children aged 1 to 4, and the heavy incidence of mortality at these ages after 1918 is the most striking feature of the analysis of mortality by age. Whilst mortality in infancy fell much more heavily on males than on females, early childhood mortality was much higher in Cocos for girls than for boys. The life table computed for the period 1918 to 1947 indicated a life expectancy of about 50 years for males and 47 years for females.     

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.     

Purposive concealment of death in household surveys in Misamis Oriental Province

Summary The randomized response technique was used in a household survey of approximately 2,000 rural and 2,000 urban households in Misamis Oriental Province in the southern Philippines in order to determine the extent of purposive concealment of death. The estimated number of deaths deliberately not revealed to the interviewers was 50 per cent or higher. Adjusted crude death rates of 11.5 and 13.4 per 1,000 population were computed for urban and rural areas, respectively, by adding estimated concealed deaths to deaths reported to the interviewers. Application of stable population techniques and of model life tables suitable to the Philippine setting, while not permitting definite conclusions, provided reasons for believing that these adjusted death rates are close to the true mortality situation in the study areas. Randomized response data further indicate that approximately 75 per cent of urban deaths and 47 per cent of rural deaths of the population studied were not registered with municipal authorities. The authors postulate that failure to register deaths with municipal authorities, together with fear of legal involvement if this failure becomes known outside the immediate neighbourhood, is a major reason for the purposive concealment of death in household surveys.     

Neo-natal and post-neo-natal mortality in a rural area of Bangladesh

Abstract An analysis of neo-natal and post-neo-natal mortality in 132 villages (population of 117,000) of Matlab thana indicates the following: (i) Neo-natal deaths accounted for 60% of the infant mortality rate of 125. This proportion was unexpectedly high since previous research had maintained that in countries with infant mortality rates over 100, neo-natal deaths account for less than one-third of all infant deaths. Since the present findings on the proportions of neo-natal deaths correspond exactly with results from an earlier registration system in East Pakistan, it is suggested that the long-accepted proposition, 'less developed' areas are characterized by lower proportions of neo-natal deaths than 'more developed' areas, be re-examined. (2) The infant death rate accounts for 36% of all deaths in the population. If the infant death rate were reduced by half the result would be a decrease in the current crude death rate from 16 to 13. Although this reduction would appear to be small, in the context of a current high growth rate of 3% (from 1966-67 to 1968-69) it exerts a sizeable impact. For example, it would take a reduction of eight points in the crude birth rate of 46 just to achieve a growth rate 2·5% under these circumstances. Obviously, continued efforts in death control without an effective birth control programme will perpetuate high rates of growth. (3) Neo-natal and post-neo-natal mortality exhibited the -expected 'U' shaped pattern with parity, and generally varied as expected with age and family size, except in the oldest age group and largest family size where the risk was smaller than in the preceding groups. An explanation for these findings is presented, based on the effect that births to high-parity women with low child mortality have upon the total neo-natal and post-neo-natal mortality rates. It was found that these births exhibit a much lower mortality risk than births to women of comparable parities and higher child mortality, and that their numbers account for the lower risk to the births in the oldest age group and largest family size. It was concluded that women with a combination of high parity and low child mortality most probably represent a group with superior socio-economic and or health conditions which contribute to the lower risk of neo-natal and post-neo-natal death.     

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.     

A method for deriving mortality estimates from incomplete vital Statistics

Summary Although they are available in many developing countries vital registration records are very little used for mortality estimation which is still mainly based on census returns. However, defective death records may yield accurate estimations of mortality. This procedure requires few data only; a sex-age distribution of the population (preferably at the middle of a period) and a sexage distribution of deaths, either derived from vital records or from census returns to questions relating to deaths during the preceding twelve months. This method is based on the observation that for a fixed age structure of the population, there is a one-one relation between the age structure of deaths (measured by the proportion of deaths at older ages) and the level of mortality (measured by the death rate above a certain minimum age). It is assumed that at ages above this minimum the rate of underregistration of deaths does not vary significantly with age. Therefore, the age distribution of registered deaths makes it possible to estimate the true proportion of deaths at older ages. This in its turn will permit the estimation of the true level of mortality, because of the relation which exists between age structure of deaths and level of mortality. The true level is then compared with the observed, to estimate the rate of underregistration, and observed age-specific death rates can be adjusted in the light of this knowledge.     

The demographic transition in the Korean peninsula, 1910-1990: South and North Korea compared

North and South Korea have both experienced demographic transition and fertility and mortality declines. The fertility declines came later in North Korea. In 1990, the population was 43.4 million in South Korea and 21.4 million in North Korea and the age and sex compositions were similar. This evolution of population structure occurred despite differences in political systems and fertility determinants. Differences were in the fertility rate and the rate of natural increase. The total fertility rate was 2.5 children in North Korea and 1.6 in South Korea. The rate of natural increase was 18.5 per 1000 in North Korea and 9.8 in South Korea. Until 1910, the Korean peninsula was in the traditional stage characterized by high fertility and mortality. The early transitional stage came during 1910-45 under the Japanese annexation. Health and medical facilities improved and the crude birth rate rose and then declined. With the exception of the war years, population expanded as a function of births, deaths, and international migration. Poor economic conditions in rural areas acted as a push factor for south-directed migration, migration to Japan, and urban migration. Next came the chaotic stage, during 1945-60. South Korean population expanded during this period of political unrest. Repatriation and refugee migration constituted a large proportion of the population increase. Although the war brought high mortality, new medicine and disease treatment reduced the mortality rate after the war. By 1955-60, the crude death rate was 16.1 per 1000 in South Korea. The crude birth rate remained high at 42 per 1000 between 1950-55. The postwar period was characterized by the baby boom and higher fertility than the pre-war period of 1925-45. Total fertility was 6.3 by 1955-60. The late transitional stage occurred during 1960-85 with reduced fertility and continued mortality decline. By 1980-85, total fertility was 2.3 in the closed population. The restabilization stage occurred during 1985-90, and fertility declined to 1.6. In North Korea, strong population control policies precipitated fertility decline. In South Korea, the determinants were contraception, rising marriage age, and increased use of abortion concomitant with improved socioeconomic conditions.     

African-american mortality at older ages: Results of a matching study

In this paper we investigate the quality of age reporting on death certificates of elderly African-Americans. We link a sample of death certificates of persons age 65+ in 1985 to records for the same individuals in U.S. censuses of 1900, 1910, and 1920 and to records of the Social Security Administration. The ages at death reported on death certificates are too young on average. Errors are greater for women than for men. Despite systematic underreporting of age at death, too many deaths are registered at ages 95+. This excess reflects an age distribution of deaths that declines steeply with age, so that the base for upward transfers into an age category is much larger than the base for transfers downward and out. When corrected ages at death are used to estimate age-specific death rates, African-American mortality rates increase substantially above age 85 and the racial “crossover” in mortality disappears. Uncertainty about white rates at ages 95+, however, prevents a decisive racial comparison at the very oldest ages.     

Estimates of vital rates for the Canadian Indians, 1960–1970

The present paper is an attempt to evaluate the registered data on Canadian Indians collected by the Department of Indian Affairs and Northern Development and to prepare vital rates for 1960–1970 using the adjusted data. A cursory examination of registered data for the purpose of developing various demographic indices and for making future estimates of population indicates certain anomalies that call for a careful appraisal of the data. The main problem is the inconsistency in the reporting of births, due largely to the late registration of births. One plausible reason for late registration may be the increased outward movement of Indians from their reserves. Indirect methods are used to adjust the number of births and infant deaths reported annually since 1960. On the basis of the adjusted data, vital rates for the Canadian Indians are calculated for the period 1960–1970. The crude death rate decreased from 10.9 in 1960 to 7.5 in 1970. The infant mortality rate registered a drastic decline, from 81.5 deaths per 1,000 births in 1960 to 34.9 in 1970. During this same time period the birth rate also declined, from 46.5 to 37.2.     

Levels and patterns of infant and child mortality in ghana

This paper attempts to measure infant and child mortality levels and also to determine their structure by utilizing the results of the 1968–1969 National Demographic Sample Survey which was conducted under the directorship of the author. Among the major problems encountered in the exercise are the adjustment of the current raw mortality data and the estimation of infant and child mortality from independent source material. The estimated infant mortality rates range from 56 per 1,000 live births in the Accra Capital District to 192 in the Upper Region during the late 1960’s. The urban rate is lower than the rural rate, 98 as against 161 per 1,000 live births. A large proportion of the deaths among children aged 0–4 occur in the second year of life, and deaths in this age group account for the bulk of the deaths within the age group 1–4 years.     

Vital rates in India 1961-71 estimated from 1971 census data

Abstract In the last decade the increase in the population of India, while, of course, very large, was smaller than predicted by official forecasts. With the use of recent census and sample registration data - in the absence of age-specific rates and adequate vital statistics - this paper provides estimates of fertility and mortality through the reverse-survival and forward-projection methods. Birth rates are estimated as 40·5-42, death rates as 18-20, and life expectancy at birth as 45-46 years. Mortality decline had been smaller than forecast but more than during any comparable period in the past, even though current mortality levels, particularly infant mortality, are still high. Males continue to have a longer life expectation than females, with a difference that has widened in the past decade. The decline of between seven and ten per cent in the crude birth rate is largely due to changes in marital fertility and to some extent to changes in age and marital composition. Because of greater decline in death rates than birth rates, the 1961-71 decade shows a higher rate of population growth than previous periods.     

Paradox found (again): Infant mortality among the Mexican-origin population in the united states

Recent research suggests that the favorable mortality outcomes for the Mexican immigrant population in the United States may largely be attributable to selective out-migration among Mexican immigrants, resulting in artificially low recorded death rates for the Mexican-origin population. In this paper we calculate detailed age-specific infant mortality rates by maternal race/ethnicity and nativity for two important reasons: (1) it is extremely unlikely that women of Mexican origin would migrate to Mexico with newborn babies, especially if the infants were only afew hours or afew days old; and (2) more than 50% of all infant deaths in the United States occur during the first week of life, when the chances of out-migration are very small. We use concatenated data from the U.S. linked birth and infant death cohort files from 1995 to 2000, which provides us with over 20 million births and more than 150,000 infant deaths to analyze. Our results clearly show that first-hour, first-day, and first-week mortality rates among infants born in the United States to Mexican immigrant women are about 10% lower than those experienced by infants of non-Hispanic, white U.S.-born women. It is extremely unlikely that such favorable rates are artificially caused by the out-migration of Mexican-origin women and infants, as we demonstrate with a simulation exercise. Further, infants born to U.S.-born Mexican American women exhibit rates of mortality that are statistically equal to those of non-Hispanic white women during the first weeks of life and fare considerably better than infants born to non-Hispanic black women, with whom they share similar socioeconomic profiles. These patterns are all consistent with the definition of the epidemiologic paradox as originally proposed by Markides and Coreil (1986).     

The Effect of Age Misreporting in China on the Calculation of Mortality Rates at Very High Ages

When mortality rates by age are calculated from recorded deaths and enumerated populations, rates at higher ages are typically in error because of misstated ages. Mortality rates for China in 1981 have been calculated from the number of deaths in 1981 in each household recorded in the 1982 census, and from the census population back-projected one year. Because age was determined from date of birth, and because persons of the Chinese culture have very precise knowledge of date of birth, the mortality rates even at high ages should be unusually accurate. This expectation is fulfilled for most of China, but severe misreporting of age is found in a province that contains a large minority of a non-Han nationality, which lacks precise knowledge of date of birth. Although the province contains only 1.3% of China's population, male death rates above age 90 for all of China are distorted seriously by the erroneous data from this location.     

Spanish Surname and Anglo Infant Mortality: Differentials Over a Half-Century

Using a half-century of death records from San Antonio/Bexar County, Texas, we examine the timing and cause structure of Spanish surname and Anglo infant mortality. Our findings show that despite the substantial disparities between ethnic-specific infant mortality rates in the early years of the study, there have been consistent declines in overall, neonatal, and postneonatal mortality for both groups, as well as a major convergence of mortality rates between Spanish surname and Anglo infants. Further, we demonstrate that the convergence is of relatively recent origin and is due primarily to shifts in postneonatal mortality. Finally, we examine the transition reflected in the cause structure of ethnic-specific infant mortality and show that the convergence was largely the result of reductions in deaths from exogenous causes. Implications for research into the "epidemiologic paradox" are discussed.     

Mortality in England and Wales from 1848 to 1947

This is a survey of the changing causes of death in England and Wales during the past 100 years. Based on the published mortality statistics of the General Register Office the framework of the survey is a series of specially prepared tables of death rates by sex, age and cause of death for the periods 1848–72, 1901–10, 1921, 1931, 1939 and 1947. Adjustments were made wherever necessary to compensate for changes in medical nomenclature and in the statistical classification of disease.

After allowance has been made for the changing age structure of the population, the male death rate at all ages in 1947 was 42% of the rate in 1846–50, and the female rate 35 %. Maximum improvement was among girls aged 5–9 years, whose death rate in 1947 was 9% of the rate 100 years before.

In 1848–72 the group to which were allocated the largest proportion of the deaths at all ages were the infectious diseases with one-third of the total; and these were followed by the respiratory, nervous and digestive diseases. In 1947, on the other hand, diseases of the circulatory system came first with rather more than one-third of the total at all ages, and these were followed by cancer.

Changes in proportionate mortality rates from various causes have been examined at successive ages from infancy to old age. There was a decline in proportionate mortality from the infectious diseases other than tuberculosis, but increased mortality from tuberculosis in the younger age groups and from violence, circulatory diseases and cancer.

The trends of absolute mortality from the various causes were also studied. The reduction in total mortality was such that whereas there were half a million deaths of civilians registered in England and Wales in 1947, the total would have been over a million had the death rates of 1848–72 still prevailed.

The article concludes with a brief review of the factors responsible for the changes that have taken place.     

Mortality in New Zealand and England and Wales

This paper compares age-specific mortality rates in England and Wales with those of New Zealand. Differences in rates are greatest at the younger age groups, and are particularly high for infants under 1 year and children between 1 and 5 years. The age-specific mortality rates for females under 25 years and for males under 35 years are analysed by causes of death in order to discover where the main differences between the two countries occur, and for infant mortality in England and Wales a further analysis has been made by social class. The greatest room for improvement in England and Wales mortality rates, as compared with New Zealand rates, is at ages under 5 years, and in infant mortality in particular the greatest differences between England and Wales and New Zealand rates by causes of death are for those causes usually associated with environmental influences.     

Paradox Revisited: A Further Investigation of Racial/Ethnic Differences in Infant Mortality by Maternal Age

I reexamine the epidemiological paradox of lower overall infant mortality rates in the Mexican-origin population relative to U.S.-born non-Hispanic whites using the 1995–2002 U.S. NCHS linked cohort birth-infant death files. A comparison of infant mortality rates among U.S.-born non-Hispanic white and Mexican-origin mothers by maternal age reveals an infant survival advantage at younger maternal ages when compared with non-Hispanic whites, which is consistent with the Hispanic infant mortality paradox. However, this is accompanied by higher infant mortality at older ages for Mexican-origin women, which is consistent with the weathering framework. These patterns vary by nativity of the mother and do not change when rates are adjusted for risk factors. The relative infant survival disadvantage among Mexican-origin infants born to older mothers may be attributed to differences in the socioeconomic attributes of U.S.-born non-Hispanic white and Mexican-origin women.     

Estimating the completeness of under-5 death registration in Egypt

To evaluate the completeness of registration of infant and child deaths in Egypt, reinterviews were conducted with families who had reported a death of a child under age 5 in the five years before the survey for two national surveys recently conducted in Egypt: the United Nations PAPCHILD survey of1990-1991 and the Egyptian Demographic and Health Survey (EDHS) of 1992. The survey instrument included questions regarding notification of the death at the local health bureau. If the family said the death had been notified, separate employees searched the health bureau records for the registration. Overall 57% of infant deaths were reported as notified and 68% of those death reports were found; the corresponding figuresfor child deaths were 89% and 74%. Using the percentage reported as notified as an estimate for completeness of registration, we adjusted upward the national infant and child mortality rates from registration data, giving values of 73 per 1,000 for infant mortality and 99 for ₅q₀ for the period 1987-1990. These values are approximately 20% above the corresponding direct estimates from the PAPCHILD and EDHS surveys.     

Socioeconomic Inequalities in Infant Mortality in Egypt: Analyzing Trends Between 1995 and 2014

This paper analyses the trend of the socioeconomic inequalities in infant mortality rates in Egypt over the period 1995–2014, using repeated cross-sectional data from the National Demographic and Health Survey. A multivariate logistic regression and concentration indices are used to examine the demographic and socioeconomic correlates of infant mortality, and how the degree of socioeconomic disparities in child mortality rates has evolved over time. We find a significant drop in infant mortality rates from 63 deaths per 1000 live births in 1995 to 22 deaths per 1000 live births in 2014. However, analyzing trends over the study period reveals no corresponding progress in narrowing the socioeconomic disparities in childhood mortality. Infant mortality rates remain higher in rural areas and among low-income families than the national average. Results show an inverse association between infant mortality rates and living standard measures, with the poor bearing the largest burden of early child mortality. Though the estimated concentration indices show a decline in the degree of socioeconomic inequality in child mortality rates over time, infant mortality rate among the poor remains twice the rate of the richest wealth quintile. Nonetheless, this decline in the degree of socioeconomic inequality in child mortality is not supported by the results of the multivariate logistic regression model. Results of the logistic model show higher odds of infant mortality among rural households, children who are twins, households with risky birth intervals. We find no statistically significant association between infant mortality and child’s sex, access to safe water, mothers’ work, and mothers’ nutritional status. Infant mortality is negatively associated with household wealth and regular health care during pregnancy. Concerted effort and targeting intervention measures are still needed to reduce the degree of socioeconomic and regional inequalities in child health, including infant mortality, in Egypt.     

Reply to Wachter

Although twins constitute only about 2.4 per cent of total births in less developed countries, they account for about 12 per cent of neonatal deaths and about nine per cent of infant deaths. Twin mortality in less developed countries has almost never been analysed systematically. We examine survival among twins as contrasted with that among singleton births by using 2692 twin observations pooled from 26 standardized Demographic and Health Surveys. Weakened by gestational and other biological complications, twins seem to be more vulnerable to detrimental demographic and household socio-economic influences than singletons. Twinning tends to amplify, or at least retain, whatever group differences exist among singleton births.