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Objectives: We examined how changes in demographic, geographic, and childbearing risk factors were related to changes in the Black-White infant mortality rate (IMR) gap over 2 decades., Methods: Using 1983-2004 Vital Statistics, we applied inverse probability weighting methods to examine the relationship between risk factors and 3 outcomes: the overall IMR gap, its birth weight component, and its conditional (on birth weight) IMR component., Results: The unexplained IMR gap (the part not related to observed risk factors) was stable, changing from 5.0 to 5.3 deaths per 1000 live births. By contrast, the explained gap declined from 4.6 to 1.9. The decline in the explained gap was driven by the changing relationship between risk factors and IMR. Further analysis revealed that most of the unexplained gap occurred among infants weighing less than 1000 grams at birth, whereas most of the explained gap occurred among infants weighing more than 1000 grams., Conclusions: The unexplained gap was stable over the last 2 decades, but the explained gap declined markedly. If the stability of the unexplained gap continues, even complete convergence of risk factors would reduce the Black-White IMR gap by only one quarter.

Objective: Racial disparities in infant and neonatal mortality vary substantially across the U.S. with some states experiencing wider disparities than others. Many factors are thought to contribute to these disparities, but state differences in fetal death reporting have received little attention. We examined whether such reporting requirements may explain national variation in neonatal and fetal mortality rates and racial disparities., Methods: We used data on non-Hispanic white and non-Hispanic black infants from the U.S. 2000-2002 linked birth/infant death and fetal death records to determine the degree to which state fetal death reporting requirements explain national variation in neonatal and fetal mortality rates and racial disparities. States were grouped depending upon whether they based the lower limit for fetal death reporting on birthweight alone, gestational age alone, both birthweight and gestational age, or required reporting of all fetal deaths. Traditional methods and the fetuses-at-risk approach were used to calculate mortality rates, 95% confidence intervals, and relative and absolute racial disparity measures in these four groups., Results: States with birthweight-alone fetal death thresholds substantially underreported fetal deaths at lower gestations and slightly overreported neonatal deaths at older gestations. This finding was reflected by these states having the highest neonatal mortality rates and disparities, but the lowest fetal mortality rates and disparities., Conclusions: Using birthweight alone as a reporting threshold may promote some shift of fetal deaths to newborn deaths, contributing to racial disparities in neonatal mortality. The adoption of a uniform national threshold for reporting fetal deaths could reduce systematic differences in live birth and fetal death reporting.

Objective: We assessed the relationships between active labor and neonatal death, neonatal brain damage, and disabling cerebral palsy in low-birth-weight infants., Study Design: A population-based cohort of 961 infants with birth weights of 580 to 2000 g and gestational ages >or=26 completed weeks. Neonatal brain damage was assessed by ultrasound scanning in the first weeks of life; disabling cerebral palsy was assessed at 2 years of age (corrected for gestational age)., Results: After being controlled for possible confounders, active labor was associated significantly with an increased risk of parenchymal echodensities/lucencies and/or ventricular enlargement (odds ratio, 2.3; 95% CI, 1.2-4.5) but not with germinal matrix/intraventricular hemorrhage (odds ratio, 1.3; 95% CI, 0.8-2.1), neonatal death (odds ratio, 1.8; 95% CI, 0.8-4.0), or disabling cerebral palsy (odds ratio, 1.6; 95% CI, 0.7-3.7). In vertex presentations only, active labor was associated with a nearly 4-fold increase in risk of neonatal death (odds ratio, 3.8; 95% CI, 1.3-10.9). In nonvertex presentations only, active labor was associated strongly with parenchymal echodensities/lucencies and/or ventricular enlargement (odds ratio, 4.3; 95% CI, 1.2-15.6) and disabling cerebral palsy (odds ratio, 8.2; 95% CI, 1.4-49.9)., Conclusion: The only adverse outcome that was associated consistently with active labor was parenchymal echodensities/lucencies and/or ventricular enlargement. Fetal presentation modified the relationships between active labor and adverse outcomes. Delivery mode (whether vaginal or cesarean delivery) was not associated with any of the outcomes that were evaluated.

Objectives: To summarize the literature on mortality rates and prevalences of major neurodevelopmental disabilities and to examine trends of these outcomes over time in extremely premature neonates., Data Sources: MEDLINE was used to search the English literature for studies published since 1970 reporting on both mortality and disability in infants born at or before 26 weeks' gestation (extremely immature [EI] cohort), with a birth weight of 800 g or less (extremely small [ES] cohort), or subgroups of these., Study Selection: Studies were included in the analysis if all of the following were reported: mortality; direct examination of 75% or more of the survivors; and the proportion of patients with at least 1 of the following disabilities: cerebral palsy, mental retardation, blindness, and deafness. Studies reporting cohorts included as a subset of cohorts in another study were excluded. Forty-two studies providing mortality and disability data for 20 cohorts of 4116 EI infants and 38 cohorts of 4345 ES infants born after 1972 met the inclusion criteria., Data Extraction: Data were abstracted from all studies that met these criteria by two of us (J.M.L. and D.E.W.), independently; the data were then cross-checked to ensure accuracy., Results: Survival averaged 41% for EI infants and 30% for ES infants, and it increased significantly with time. In contrast to mortality, the prevalences of major neurodevelopmental disabilities among survivors have not changed over time. The most common major disability was mental retardation, found in 14% of EI and ES survivors. Cerebral palsy was found in 12% of EI survivors and 8% of ES survivors, blindness was found in 8% of EI and ES survivors, and deafness was found in 3% of EI and ES survivors. Overall, 22% of EI survivors and 24% of ES survivors were classified as having at least 1 major disability. Each 100 EI or ES livebirths yielded 7 children with major disabilities; this prevalence was correlated with survival across cohorts., Conclusions: The prevalence of disabilities had not changed among EI or ES survivors with increasing survival. However, increasing survival of these infants has resulted in a steadily increasing prevalence of children with disabilities.

In Canada between 1958 and 1977 the neonatal mortality dropped by more than 50%. the decline was most prominent from 1963 and was almost entirely due to an improvement in neonatal birthweight-specific mortality, which suggests an improvement in perinatal medical care. The timing and pattern of the decline are similar to those reported for the United States. There was a transient increase in the incidence of low and very low birthweight in both countries in the late 1960s. The cause of this increase remains unexplained.

In an analysis of all singleton births and neonatal deaths with known birth weights and gestational ages in New York City maternity services during a three-year period (1976 to 1978), intensive care services at the hospital of birth were found to influence mortality only in preterm (less than 37 weeks' gestation) or low-birth-weight infants (less than 2251 g). By contrast, for infants who were born at term and of normal birth weight, mortality rates did not differ by level of perinatal care available at the hospital of birth. On the average, preterm and low-birth-weight infants were at a 24% higher risk of death if birth occurred outside of a level 3 center, regardless of whether birth occurred at a level 1 or level 2 hospital. Preterm and low-birth-weight infants, though constituting only 12% of births, accounted for 70% of neonatal deaths in New York City. The remaining infants, ie, those born at term and of normal birth weight, who experienced no measurable mortality advantage when born in a level 3 hospital, accounted for 88% of all births.

To maintain a stable over-all prevalence of handicap, the rate of handicap among survivors must decline in parallel to the decline in mortality among live births. The 24 per cent decline in mortality among low-birthweight infants in New York City between 1962 and 1976 requires a 35 to 39 per cent decline in the rate of neurological impairment among low-birthweight survivors simply to avoid the production of an increased number of handicapped children in the population as a whole. Such evidence as we have suggests that the declining morbidity may not be keeping pace with the recent declines in mortality: thus, although more healthy survivors will result from newborn intensive care, a modest increase in the prevalence of handicap may also ensue.

In New York City, newborn units classified as level 1 (no intensive care) frequently transfer low-birth-weight infants to units classified as level 3 (complete intensive care), but level 2 units (those with intermediate levels of care) transfer rarely. As deaths occurring in the first hours of life are unlikely to be affected by infant transport services, early (first four hours), late (four hours to 28 days), and overall neonatal death rates were separately examined at each of the three levels of care for singleton live-births weighing 501 to 2,250 g. As previously reported, overall neonatal mortality (adjusted for birth weight, gestational age, sex, and race) for births at level 1 units (163.0/1,000) and level 2 units (168.1/1,000) was similar, and rates for births at level 3 (128.0/1,000) were significantly lower. Mortality up to four hours, and from four hours to 28 days, however, differed between level 1 and level 2 units. Among early deaths, the mortality for level 1 births was 68.0/1,000, significantly higher than both the rate for level 2 births (46.0/1,000) and for level 3 births (40.6/1,000). Between four hours and 28 days, mortality relative to level 3 improved for level 1 births, but worsened for level 2 births. For infants with birth weight less than 1,251 g, for whom transport rates from level 1 units are highest, mortality in level 1 births was higher than in level 2 births only until 18 hours of life; thereafter, level 2 mortality was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Perinatal mortality has several components which may have distinct epidemiologic features. In an investigation of the total singleton birth population of New York City in 1976-1978 (n = 320,726), the authors divided perinatal mortality into four components: late fetal deaths that occurred before labor (late antepartum fetal deaths), fetal deaths during labor (intrapartum fetal deaths), neonatal deaths, and perinatal deaths attributed to congenital anomalies, and they assessed the relation of each of these to maternal age and parity, controlling for relevant confounding factors. In analyses which controlled for prior fetal loss, type of service (public vs. private), race, marital status, and mother's educational attainment in a multiple logistic regression model, the authors found that: 1) increasing maternal age was strongly associated with antepartum fetal deaths but not with intrapartum fetal deaths, while older maternal age was also associated with perinatal deaths attributed to congenital anomalies; 2) high parity bore a strong relationship to intrapartum fetal deaths, but none to antepartum fetal deaths, neonatal deaths, or congenital anomaly deaths; and 3) for neonatal death, there was a statistically significant (p less than 0.001) interaction between parity and age such that mothers over 34 years old having their first birth were at especially high risk.

We have examined the relationship between the rate of very low-birth-weight deliveries in a population and the neonatal mortality of that population on three ecologic levels: in one hospital over a 12-year span; among the 50 states and the District of Columbia; and among 13 industrialized nations. In each of the three sets of populations the VLBW rate is an excellent predictor of neonatal mortality, accounting for about three-quarters of the variance in the outcome in all of the populations studied. The relatively high neonatal mortality of the United States as compared to that in some other industrialized nations is primarily attributable to its disadvantageous birth-weight distribution. Holding the adverse birth-weight distribution constant, the United States appears to do better than most of these nations in neonatal mortality. The weight distribution of live births in any population is closely linked to indices of social class. Survival of infants at a given birth weight, however, might well be a function of perinatal care. Since weight-specific mortality rates for populations are not widely available, examination of the variance in neonatal mortality rates once the VLBW rate is held constant might be a first step in comparing the quality of medical care for newborn infants among different populations.

To test the hypothesis that the recent substantial decline in the United States neonatal mortality rate (20.0/1000 in 1950 to 11.6/1000 in 1975) is associated with improvements in perinatal medical care, we examined this change in relation to the two primary components which determine neonatal mortality: birthweight distribution and birthweight-specific mortality. No improvement in the weight distribution of U.S. live births has occurred during this 25-year period, indicating that the change in neonatal mortality is attributable to improved survival for one or more birthweight groups. Decline in the mortality rate in the first 15 years was slow; three-fourths of the decline in the entire 25-year period occurred since 1965. With the exception of perinatal medical care, factors known to affect survival at a given birthweight have not changed in prevalence in the 25-year period. It is a plausible hypothesis that improved perinatal medical care is a major factor in declining neonatal mortality in the U.S.

This study examines the utility of birth weight-specific neonatal mortality rates in removing the confounding effects, in comparisons of mortality in low birth weight infants, of several factors that influence crude neonatal mortality. For this purpose, the effects of social, demographic, and biological attributes of mothers on the mortality of their low birth weight babies were examined in the total population of infants weighing 501-2000 gm born in New York City in 1976, 1977, and the first 11 months of 1978 (N = 10,187). The results confirm previous observations that race, sex, and gestational age-for-weight all exert significant influences on mortality even within narrow (250 gm) birth weight bands. However, mothers' education, number of prenatal visits and whether delivery was on private or ward service, all variables which substantially affect crude neonatal mortality, had no overall effect on weight-specific mortality in the weight range under consideration. Two other socioeconomic indicators, whether delivery was financed by Medicaid, and the marital status of the mother, did significantly affect weight-specific mortality, but their effects were abolished when gestation, race, and sex were entered into the analysis. Although neither maternal age nor parity had any significant individual effects on low birth weight mortality, a linear trend towards lower mortality in older mothers was discovered, and certain age-parity combinations experienced significantly elevated or reduced mortality. In general, weight-specific mortality in low birth weight infants is little influenced by the socioeconomic circumstances of their mothers, particularly when race, sex, and gestation are taken into account. Weight-specific neonatal mortality can therefore be a useful tool in the analysis of the effectiveness of perinatal medical care given to low birth weight infants.

In recent years, neonatal mortality rates for low-birthweight infants have declined both in neonatal intensive care units and in several populations in the industrialized world. With regard to impairment among surviving low-birthweight infants, studies from newborn intensive care units show considerable variation in the reported rates of handicaps. Much of this variation arises from a lack of uniform criteria for diagnosis, sample selection and follow-up, factors further compounded by small sample size. At the present time it is premature to conclude that changes in newborn care have either lowered or raised rates of impairment among surviving low-birthweight infants.

We examined the neonatal mortality rates of low-birth-weight infants (501 to 2250 g) born between 1976 and 1978 in three kinds of hospitals in New York City: those with newborn-intensive-care units (Level 3), those with capabilities for the care of most premature infants (Level 2), and those without any special facilities for premature newborns (Level 1). Among 13,560 singleton low-birth-weight infants, the adjusted neonatal mortality rate for Level 3 hospitals was 128.5 per thousand live births - significantly lower (P less than 0.001) than the rates for both level 2 (168.1) and Level 1 units (163.0). The association of level of care with mortality could not be accounted for by differences between groups in social or demographic status, in prenatal care, or in medical complication of pregnancy. We infer that birth at a Level 3 center lowers neonatal mortality in low-birth-weight infants. However, only 34 per cent of the patients in this study were born in such units.