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.     

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.     

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.     

Epidural analgesia during birth and adverse neonatal outcomes: A population-based cohort study

BackgroundIn general, epidural analgesia is considered a safe and efficient way to relieve pain during active labour and is increasingly used in childbirth. It is well documented that epidural analgesia during birth has benefits but also adverse effects. However, evidence is limited on how epidural analgesia influences neonatal outcome in a low-risk population of birthing women.AimTo examine low Apgar score, foetal hypoxia and admission to the neonatal intensive care unit in neonates of low-risk women receiving epidural analgesia during birth.MethodsA cohort study using registry data to investigate a population of 23,272 low-risk women giving birth at a university hospital.ResultsEpidural analgesia was used in 21.6% of low-risk women during birth. Low Apgar score, foetal hypoxia, and admission to the neonatal intensive care unit were found in 0.6%, 0.6%, and 10.0%, respectively in neonates of mothers receiving epidural analgesia during birth compared to 0.3%, 0.6%, and 5.6%, respectively in the non-exposed group. Epidural analgesia was associated with low Apgar score, adjusted odds ratio 1.76 (95% CI 1.07–2.90) and admission to the neonatal intensive care unit, adjusted odds ratio 1.43 (95% CI 1.26–1.62). A mediation analysis indicates the impact of epidural analgesia on adverse neonatal outcomes was mediated by obstetric complications like maternal fever, labour augmentation, and foetal malpresentation.ConclusionThis study found use of epidural analgesia during birth in low-risk pregnant women was associated with infant low Apgar score and admission to the neonatal intensive care unit.     

Prenatal Health,Educational Attainment,and Intergenerational Inequality: The Northern Finland Birth Cohort 1966 Study

In this article, we study the effects of prenatal health on educational attainment and on the reproduction of family background inequalities in education. Using Finnish birth cohort data, we analyze several maternal and fetal health variables, many of which have not been featured in the literature on long-term socioeconomic effects of health despite the effects of these variables on birth and short-term health outcomes. We find strong negative effects of mother’s prenatal smoking on educational attainment, which are stronger if the mother smoked heavily but are not significant if she quit during the first trimester. Anemia during pregnancy is also associated with lower levels of attained education. Other indicators of prenatal health (pre-pregnancy obesity, mother’s antenatal depressed mood, hypertension and preeclampsia, early prenatal care visits, premature birth, and small size for gestational age) do not predict educational attainment. Our measures explain little of the educational inequalities by parents’ class or education. However, smoking explains 12%—and all health variables together, 19%—of the lower educational attainment of children born to unmarried mothers. Our findings point to the usefulness of proximate health measures in addition to general ones. They also point to the potentially important role played by early health in intergenerational processes.     

Polygyny and child survival in Nigeria: Age-dependent effects

Mortality risks under age five are estimated using data from the 1990 Nigerian Demographic and Health Survey for children in monogamous and polygynous families. Integrating existing theories on polygyny’s relationship with infant and child mortality and some demographic concepts, the study shows that polygyny has different effects on infant and child mortality at different ages. The results indicate that polygyny does not have a significant effect on neonatal mortality (age less than one month). In contrast to the results of previous research, polygyny is significantly associated with lower child mortality during the post-neonatal period (1–11 months), but not during childhood (12–59 months). The study found socio-economic factors to be important confounders of the relationship between polygyny and mortality during the neonatal and post-neonatal periods. The protective effect of polygyny during the post-neonatal period suggests the need to further investigate circumstances that may favour post-neonatal child survival in polygynous families including availability of childcare.     

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.     

The Effect of Prenatal Natural Disaster Exposure on School Outcomes

This study looks at the impact of exposure to natural disasters during pregnancy on the educational outcomes of North Carolina children at the third grade level. A broad literature relates negative birth outcomes to poor educational performance, and a number of recent studies have examined the effect of prenatal exposure to natural disasters on birth outcomes. This study takes the next step by considering how prenatal exposure affects later outcomes. Combining North Carolina administrative data on births and school performance with disaster declarations from the U.S. Federal Emergency Management Agency (FEMA) allows for the identification of children who were exposed to disasters during prenatal development. These children are compared with other children born in the same county who were not exposed to disasters while in utero. Regression results suggest that children exposed to hurricanes prenatally have lower scores on third grade standardized tests in math and reading. Those exposed to flooding or tornadoes also have somewhat lower math scores. Additionally, results suggest that these negative effects are more concentrated among children in disadvantaged subgroups, especially children born to black mothers. However, no evidence exists that these effects are mediated by common measures of birth outcomes, including birth weight and gestational age.     

Gynecologic age is an important risk factor for obstetric and perinatal outcomes in adolescent pregnancies

BackgroundAdolescent pregnancy is an important public health problem. Physiological maturity affects obstetric and perinatal outcomes. Almost all assessments of adolescent pregnancies are based on chronological age. Gynecologic age (GA) is defined as age in years at conception minus age at menarche and it is an indicator of physiological maturity.AimTo compare obstetric and perinatal outcomes between adult and adolescent pregnancies as categorized according to GA.MethodsIn this retrospective study, 233 adolescent pregnant women were divided into two groups based on GA ≤ 3 years (101 women) and GA > 3 years (132 women). Their obstetric and perinatal results were compared with 202 adult pregnancies who gave birth in the same period.FindingsGestational age at delivery, APGAR scores, birth weight, and incidence of preterm birth, admission to neonatal intensive care unit (NICU), intrauterine growth restriction, low birth weight, and premature rupture of membranes were significantly different between the study groups. Compared to adolescent pregnancies with GA > 3 years, adolescent pregnancies with GA ≤ 3 years had significantly lower birth weight, gestational age, APGAR scores, and significantly higher incidence of intrauterine growth restriction, low birth weight and admission to NICU.ConclusionLow GA is associated with an increased rate of obstetric and perinatal complications in adolescent pregnancies. Although the main aim is the prevention of adolescent pregnancies, a detailed evaluation of such pregnancies including determination of the gynecological age together with a multidisciplinary approach may decrease potential complications.     

Infant Mortality and Socioeconomic Status: New Bottle,Same Old Wine

This paper presents the results of an ecological analysis of the relationship between infant mortality and economic status in metropolitan Ohio for the period 1960–2000. The data examined are centered on the five censuses undertaken during this 40-year period. The basic unit of analysis is the census tract of mother’s usual residence, with economic status being determined by the percentage of low income families living in each tract. For each of the five periods covered, census tracts were aggregated into broad income areas and three-year average infant mortality rates were computed for each area, by age, sex, race and exogenous-endogenous causes of death. The most important conclusion to be drawn from the data is that in spite of some very remarkable declines in infant mortality at all class levels since 1960, there continues to be a very clear and pronounced inverse association between income status and infant mortality. Indeed, the evidence indicates that the relationship has become stronger over the years. These observations are applicable for both sexes, for whites and nonwhites, for neonatal and postneonatal deaths, and for both major cause of death groups. It is concluded that while public health programs are important, any progress in narrowing this long-standing differential is unlikely unless ways can be found to enhance the economic well-being of the lower socioeconomic groups.     

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.     

Review of educational interventions to increase traditional birth attendants’ neonatal resuscitation self-efficacy

Background

Annually, up to 2.7 million neonatal deaths occur worldwide, and 25% of these deaths are caused by birth asphyxia. Infants born in rural areas of low-and-middle-income countries are often delivered by traditional birth attendants and have a greater risk of birth asphyxia-related mortality.

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.     

Maternal pre-pregnancy body mass index,gestational weight gain influence birth weight

Background

Evidence suggests that pre-pregnancy body mass index and gestational weight gain have impact on pregnancy and birth weight, yet whether maternal gestational weight gain has a differential effect on the rates of adverse birth weight among women with different pre-pregnancy body mass index categories are unknown.

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.     

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.     

Perspectives on antenatal education associated with pregnancy outcomes: Systematic review and meta-analysis

BackgroundMany studies on the relation between maternal health and infant health, including the effect of structured antenatal education, have been published and expanded over the years.AimInvestigate the impact of various antenatal education programmes on pregnancy outcomes to aid the development of future guidelines related to maternal and foetal health.MethodsBibliographic databases (Cochrane, PubMed, EMBASE, CINAHL, Korean Studies Information Service System) were searched up to November 2018, following the PICO criteria: population (pregnant women), intervention (antenatal education), comparison (not specified), and outcome (maternal and foetal outcome including physical or mental health components).FindingsWe included 23 eligible studies consisting of 14 controlled trials and 9 observational studies. The maternal physical outcomes depending on participation in antenatal education were not significantly different; however, the caesarean birth rate was lower in the antenatal education group (relative risk, RR, 0.90; 95% confidence interval, CI, 0.82–0.99), as was the use of epidural anaesthesia (RR, 0.84; 95% CI, 0.74–0.96). The maternal mental health outcomes of stress and self-efficacy significantly improved in the antenatal education group, although there was no difference in anxiety and depression. The foetal outcomes of birth weight or gestational age at birth were also not different between the groups.ConclusionAntenatal education can reduce maternal stress, improve self-efficacy, lower the caesarean birth rate, and decrease the use of epidural anaesthesia; however, there is limited evidence of its effects on maternal or foetal physical outcomes. Therefore, antenatal education should be standardised to elucidate its actual mental and physical health effects.     

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.     

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.