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.     

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.     

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.     

Registration completeness and international comparisons of infant mortality

The physical development of the live born infant is the single most important variable governing its survival: infant mortality among those weighing 2,500 grams (5 1/2 pounds) or less at birth is 17 times the mortality among those weighing more than 2,500 grams at birth. The variation in mortality according to birth weight (or gestation) is greater than for subclasses of color, sex, maternal age, or birth order. Infant mortality in the United States is significantly higher than in a number of other countries e.g., Sweden, Netherlands, Norway. The difference is thought, by some, to be due to underregistration of low birth weight infants in other countries. In this paper, distributions of live births by birth weight for Denmark, England and Wales, New Zealand, and the United States, and infant mortality data for Denmark and the United States are examined. The data do not support a hypothesis of gross underregistration of live born infants in other countries. The results indicate that some index of physical development (birth weight, gestation, or a combination of both) should be included in any appraisal of infant mortality.     

The effects of maternal smoking on infant health

Maternal smoking has serious consequences for the developing fetus and infant, including a higher probability that the infant will be born prematurely and at low birth weight, will require admission to neonatal intensive care, and die during infancy. Data from Alabama birth certificates for births occurring between 1988 and 1991 were analyzed using log linear methods to calculate relative risks of adverse pregnancy outcomes and infant death. Smoking by mothers during pregnancy is associated with an elevated risk of infant death, low birth weight, and prematurity, controlling for mother's educational attainment, age, marital status, race, and trimester prenatal care was initiated. Smoking was also associated with a higher rate of admission to neonatal intensive care and to deaths from SIDS and respiratory causes. Reducing maternal smoking can contribute to a reduction of premature and low weight births and infant deaths. Because of the difficulty of stopping smoking, efforts need to be directed at preventing younger women from beginning to smoke.An earlier version of this paper was presented at the Southern Demographic Association annual meeting in New Orleans in October 1993.     

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.     

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.     

Premature birth and the changing composition of newborn infectious disease mortality: Reconsidering “exogenous” mortality

Linked death and birth records from San Antonio, Texas reveal that infectious infant mortality is increasingly a function of premature birth and low birth weight. Between 1935 and 1944, 4% of infectious infant deaths had associated causes involving prematurity and related conditions; by 1980, 25% of infectious infant deaths involved prematurity and more than 40% of those infants weighed less than 2,500 grams. The shift in birth-weight composition results almost entirely from an increase in very low-weight births. Under conditions of advanced perinatal technology, infectious infant mortality should no longer be viewed as wholly exogenous. These findings further undermine the contemporary relevance of the exogenous-endogenous distinction.     

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 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.     

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.     

Revising Infant Mortality Rates for the Early Twentieth Century United States

Accurate vital statistics are required to understand the evolution of racial disparities in infant health and the causes of rapid secular decline in infant mortality during the early twentieth century. Unfortunately, U.S. infant mortality rates prior to 1950 suffer from an upward bias stemming from a severe underregistration of births. At one extreme, African American births in southern states went unregistered at the rate of 15 % to 25 %. In this study, we construct improved estimates of births and infant mortality in the United States for 1915–1940 using recently released complete count decennial census microdata combined with the counts of infant deaths from published sources. We check the veracity of our estimates with a major birth registration study completed in conjunction with the 1940 decennial census and find that the largest adjustments occur in states with less-complete birth registration systems. An additional advantage of our census-based estimation method is the extension backward of the birth and infant mortality series for years prior to published estimates of registered births, enabling previously impossible comparisons and estimations. Finally, we show that underregistration can bias effect estimates even in a panel setting with specifications that include location fixed effects and place-specific linear time trends.     

Comment on “compromised birth outcomes and infant mortality among racial and ethnic groups”

Frisbie, Forbes, and Pullum (1996) show that it is meaningful to account for low birth weight, preterm delivery, and intrauterine growth-retardation when analyzing differences in compromised birth outcomes and infant mortality among racial and ethnic groups. I compare their findings for the 1987 U.S. birth cohort with findings for the 1988 U.S. birth cohort, using linked birth and infant death vital statistics from the National Center for Health Statistics. I focus on their calculation of fetal growth curves, which are highly at odds with the curves commonly used in the obstetric and pediatric literature. I compare birth outcome distributions and infant death probabilities using Frisbie et al. 's method and other standards. I conclude that Frisbie et al. 's method is not suited for the study of intrauterine growth-retardation at the population level because of the major flaws in gestational age measurement that exist in the type of data they use. An appropriate alternative is to apply a standard of normal intrauterine growth derived from antenatal estimation of fetal weight-for-gestational-age to the vital statistics data.     

Some aspects of the relationship between the levels of infant mortality and fertility in the ESCAP region

The death of a child within the first year of life is a crucial factor in fertility decisions in a developing country. The infant mortality rate gives a close, inverse indication of the socioeconomic conditions of a country. This paper presents studies by Brass, Rutherford, Chowdhury, Khan and Chen, Agrawal, Iskander and Jones, in summary/abstract form. It concludes that the probabilities of survival are poorer for births of older women and/or higher parities. Early child deaths may increase the total period of exposure to the risk of conception. A lower infant and child mortality norm calls for fewer births to meet the needs for survivors. Child replacement motivational response seems to be strongest with the birth immediately following a death event. Agrawal analyzed the interval between successive births of 1107 women of Patna, Pakistan, according to the age of mother and sex and fate of the previous child. He observed that if a child died shortly after its birth, often a new pregnancy began within a short interval. The interval between 2 consecutive live births when the previous child was male and alive was greater than when the previous child was female and alive. The interval between 2 births was reduced if the child died in infancy and specially if this was a male child.     

Race/Ethnicity/Nativity Differentials and Changes in Cause-Specific Infant Deaths in the Context of Declining Infant Mortality in the U.S.: 1989–2001

Using data from the national linked birth/infant death cohort files, we examined race/ethnicity/nativity disparities and changes in infant mortality due to the five leading causes of infant death between 1989 and 2001. Our results indicate substantial decreases in infant mortality from three causes (congenital anomalies, sudden infant death syndrome, and respiratory distress syndrome) for which specific perinatal health innovations emerged or were expanded. However, for these three causes, the relative disparities in infant mortality between infants born to U.S.-born black women as compared to infants of U.S.-born white women increased following the introduction (or expansion) of beneficial interventions. Among infants of U.S.-born Mexican American mothers, the findings differed. In the static comparisons, our results show the often-reported similarity in the risk of death of these babies compared to those born to non-Hispanic white mothers. However, when changes over time were modeled, there was an erosion of the relatively favorable survival chances of Mexican American infants. Our models show little change in the relative risk of death for infants of immigrant women. Regarding the other two causes (disorders relating to short gestation and unspecified low birth weight and maternal complications) for which no efficacious innovations occurred, either little change or actual increases in risks were observed. Future studies and health policy efforts should be geared toward further understanding and aggressively working to close infant mortality gaps, especially for infants of U.S.-born black mothers—an effort that will be facilitated by research focused on cause-specific infant mortality.     

The impact of induced abortion on black and white birth outcomes in the United States

This paper examines the impact of induced abortion on birth outcomes by treating abortion as an endogenous input into the production of infant health. To gauge the direct and indirect effects of abortion, three measures of infant health are considered simultaneously: the neonatal mortality rate, the percentage of low-weight births, and the percentage of preterm births. All three are race specific and all pertain to large counties in the United States in 1977. The results suggest that by preventing unwanted births, abortion enhances the survivability of newborns of a given birth weight and improves the distribution of births among high-risk groups.     

The increasing racial disparity in infant mortality: Respiratory distress syndrome and other causes

Although substantial declines in infant mortality rates have occurred across racial/ethnic groups, there has been a marked increase in relative black-white disparity in the risk of infant death over the past two decades. The objective of our analysis was to gain insight into the reasons for this growing inequality on the basis of data from linked cohort files for 1989-1990 and 1995-1998. We found a nationwide reversal from a survival advantage to a survival disadvantage for blacks with respect to respiratory distress syndrome over this period. The results are consistent with the view that the potential for a widening of the relative racial gap in infant mortality is high when innovations in health care occur in a continuing context of social inequality. As expected, the results for other causes of infant mortality, although similar, are less striking. Models of absolute change demonstrate that among low-weight births, absolute declines in mortality were greater for white infants than for black infants.     

Race/ethnic differentials in heavy weight and cesarean births

Objectives: The general objectives of this research are tofurther our understanding of the distribution and incidence of heavy weight births and to examine differentials in the use of cesarean section as a response to macrosomia in models that are more broadly comparative by race/ethnicity than any that have heretofore been estimated. Methods: The data are drawn from the combined 1989–1991 NCHS Linked Birth/Infant Death Cohort Files,a data set of over 12 million live births and over 100,000 infant deaths that allows for highly reliable estimations for relatively small race/ethnic sub populations. Results: The results confirm that previously identified determinants of macrosomia such as maternal diabetes,maternal weight gain, parity and a previous heavy weight infant are highly predictive of a macrosomic birth, independent of race/ethnic effects. With respect to the management of heavy weight births, race/ethnic differentials exist in the odds of a cesarean delivery, theprocedure most often used to limit the risks of a macrosomic delivery.     

Population statistics] as of July 1, 2000

This Mahidol Population Gazette presents Thailand's population and demographic estimates as of July 1, 2000, using the standard techniques of demographic analysis. The paper provides estimates of Thailand's total population, population by sex, population in urban and rural areas, population by region, and by age group. In addition, figures of crude birth and death are listed per 1000 population, natural growth rate, and infant mortality rate per 1000 live births, male and females' life expectancy at birth and at age 60, total fertility rate, contraceptive prevalence rate. The number of the aged population in 2020 is also presented. Presented in a bar graph is a population pyramid for Thailand in the year 2000, illustrating male and females' age and year of birth.