Decrease in infant mortality in New York City after 1989

Reduction in neonatal mortality in Chile between 1990 and 2000

OBJECTIVE

Our objective with this article was to describe the declining trend in neonatal mortality in Chile between 1990 and 2000 and examine potential causal factors.

METHODS

Descriptive analysis of data that were provided by the Chilean Ministry of Health on all approximately 2,900,000 births occurred in Chile between 1990 and 2000. Total neonatal mortality rates (<28 days), and birth weight-specific and gestational age-specific mortality rates from 1990 to 2000 were analyzed by year. Public health interventions that were implemented during the 1990s were reviewed to assess their potential influence on the observed trends in neonatal mortality.

RESULTS

The neonatal mortality rate between 1990 and 2000 decreased from 8.3 to 5.7 per 1000 live births. This decline was not associated with decreases in the proportion of low birth weight and preterm infants but rather with declines in birth weight-specific and gestational age-specific mortality rates. Examination of the trends in birth weight-specific and gestational age-specific mortality rates showed that a marked proportional decrease in mortality rates was achieved among infants who weighed <1500 g and were delivered before 32 weeks. It is plausible, both biologically and temporally, that the observed trends in the reduction in birth weight-specific and gestational age-specific mortality rates are associated with the introduction of specific sector-wide interventions that aim to improve newborn care in very preterm and low birth weight infants.

CONCLUSIONS

Important reductions in newborn mortality in developing countries are possible with the implementation of effective neonatal care interventions.

Does reducing infant mortality depend on preventing low birthweight? An analysis of temporal trends in the Americas

Low birthweight (LBW) is highly associated with death during infancy, and countries with the highest LBW rates also have the highest infant mortality rates. We compared temporal trends in LBW with both overall and birthweight-specific infant mortality in United States, Canada, Argentina, Chile, and Uruguay over two time periods, using cohort and cross-sectional analysis of national population-based vital statistics for 1985-89 and 1995-98. Infant mortality diminished substantially (RR = 0.60-0.80 for the later vs. earlier periods) and to a similar degree in all birthweight categories in all five study countries, despite an increase in LBW in the US and Uruguay, minimal changes in Canada and Argentina, and a decrease in Chile. The strength of the (positive) association between LBW and overall infant mortality diminished over the two time periods (from r(s) = +0.80 to +0.25 and RR per SD increase in LBW rate from 2.13 [2.09, 2.17] to 1.76 [1.74, 1.79]). The proportion of infant deaths occurring among LBW infants was negatively correlated with overall infant mortality in both time periods (r(s) = -0.30 and -0.60, RR = 0.68 [0.67, 0.68] and 0.47 [0.46, 0.47]). Developed and less developed countries in the Americas have succeeded in reducing infant mortality in all birthweight groups despite inconsistent changes in LBW rates, and none has achieved this success primarily by reducing LBW. Although our results are not necessarily generalisable to the least developed countries in South Asia and sub-Saharan Africa, it is likely that all countries can substantially reduce their infant mortality rates by improving the care of infants at normal and low birthweights.

Income inequality and infant mortality in New York City

A series of studies have demonstrated that people who live in regions where there are disparities in income have poorer average health status than people who live in more economically homogeneous regions. To test whether such disparities might explain health variations within urban areas, we examined the possible association between income inequality and infant mortality for zip code regions within New York City using data from the 1990 census and the New York City Department of Health. Both infant mortality and income inequality (percentage of income received by the poorest 50% of households) varied widely across these regions (range in infant mortality: 0.6-29.6/1,000 live births; range in income inequality: 12.7-27.3). An increase of one standard deviation in income inequality was associated with an increase of 0.80 deaths/1,000 live births (P <.001), controlling for other socioeconomic factors. This finding has important implications for public health practice and social epidemiological research in large urban areas, which face significant disparities both in health and in social and economic conditions.

The epidemiology of adverse pregnancy outcomes: an overview

This paper provides an overview of the occurrence, etiology and temporal trends of adverse pregnancy outcomes. Disparities between developed and developing countries are highlighted for maternal mortality, infant mortality, stillbirth and low birth weight. The higher rate of low birth weight in developing countries is primarily due to intrauterine growth restriction rather than preterm birth. Much of the excess intrauterine growth restriction is caused by short maternal stature, low prepregnancy body mass index and low gestational weight gain (due to low energy intake). No important contribution has been established for micronutrient intake, nor have different fetal growth trajectories been demonstrated to reflect the timing of exposure to nutritional or other etiologic factors. Infant mortality has declined substantially over time both in developed and developing countries despite no decline (and even an increase) in low birth weight. Several developed countries have reported a temporal increase in fetal growth in infants born at term, a reduction in stillbirth rates and prevention of neural tube defects. More progress is required, however, in understanding the etiology and prevention of preterm birth.

Temporal and spatial pattern of infant mortality in Germany after unification

OBJECTIVES

After unification in 1990 the two parts of Germany underwent a complex process that has led to convergence of infant mortality. The pattern of change did, however, differ in east and west. This study investigates whether these differences conceal a complex pattern of heterogeneity at the regional level.

METHODS

Examination of routine data on infant, neonatal and postneonatal mortality. Time trends in the 16 federal states of Germany (Länder) from 1991 to 1997 were studied using a log-linear model.

RESULTS

In 1991, infant mortality was higher in almost all eastern Länder than in the west. By 1997, this east-west gap had disappeared. Over this period, infant mortality fell in all Länder but one. The decline was steepest in the east, ranging from 31% to 52%. Improvements were largely due to steep declines in both neonatal and postneonatal mortality.

CONCLUSIONS

This study shows that, at the time of unification, there was an almost complete demarcation between east and west, a pattern that disappeared by 1997. There is, however, still a substantial regional variation in infant mortality that is largely determined by postneonatal mortality.

Mortality and time to death in very low birth weight infants: California, 1987 and 1993

BACKGROUND

Recent advances in perinatal technology have dramatically increased the survival of very low birth weight (VLBW) infants (<1500 g). The possibility that these advances may also prolong the time to death and increase pain and suffering has been of concern, but there have been no population-based evaluations of this issue.

METHODS

Infant, neonatal, and postneonatal mortality rates and time to death for infants 500 to 749 g, 750 to 999 g, 1000 to 1499 g, and all VLBW infants born during 1987 were compared with those outcomes for infants born in 1993 using statewide California linked birth/death cohort files. To assess the effects of improved survival and changes in time until death, we calculated the total days of life preceding an infant death per 1000 live born infants (TDD).

RESULTS

VLBW infants comprised.96% of California's live births in 1987 and.92% of those in 1993. Between 1987 and 1993, VLBW infant mortality rate decreased 28.4% (from 290.7 to 208.3 per 1000 live born VLBW infants), VLBW neonatal mortality rate decreased 30. 3% (from 244.5 to 170.4), and VLBW postneonatal mortality rate decreased 25.3% (from 61.2 to 45.7 per 1000 VLBW alive at 28 days; P <.05 for each rate). Infant mortality rates decreased by 18.8% (718. 1 to 583.0 per 1000) for infants 500 to 749 g, 43.3% (375.1 to 202. 6) for infants 750 to 999 g, and 40.1% (127.9 to 76.7) for infants 1000 to 1449 g (P <.05 for each group). Neonatal mortality and postneonatal mortality rates also decreased in all 3 VLBW subgroups. These reductions in mortality rates were not accompanied by a significant difference in the distribution of times to death or a significant increase in the average time to death for all VLBW infants (22.0 vs 23.6 days) or for those with birth weights of 500 to 749 g (12.7 vs 71.5 days). Reduced mortality in larger infants was accompanied by an increase in the average time to death, from 24. 3 to 32.5 days in infants 750 to 999 g and from 32.3 to 47.0 days in infants 1000 to 1449 g. TDD decreased from 6410 to 4908 days for all VLBW infants. TDD was also reduced 26.4% (2401 days), 24.3% (2115 days), and 22.5% (1043 days) for the 3 VLBW birth weight groups.

CONCLUSIONS

Both mortality rate and timing of death are important when assessing the impact of advances in perinatal technology. Although the average time to death was significantly increased in VLBW infants weighing >750 g, between 1987 and 1993, advances in perinatal technology dramatically decreased VLBW mortality. In the State of California in 1993, this resulted in 452 fewer VLBW deaths and 8233 fewer days preceding a VLBW death than expected.

Neonatal and postneonatal mortality in Germany since unification

BACKGROUND

After unification, the gap in infant mortality rates between the two parts of Germany widened until 1996 before converging. The reasons for these changes have not, so far, been apparent.

OBJECTIVES

To investigate trends in neonatal and postneonatal mortality in the eastern (the new Länder) and western (the old Länder) part of Germany after unification in 1990 and to identify the scope for further improvement.

DESIGN

Examination of trends in birth weights, birth weight specific neonatal mortality and cause specific postneonatal mortality in the two parts of Germany from 1990 to 1996 and 1997 by analysing routinely available vital statistics data.

RESULTS

In both parts of Germany, neonatal mortality fell considerably, by 33 per cent in the east and 17 per cent in the west, from 4.5 and 3.5 per thousand live births in 1990 to 3.0 and 2.9 in 1997, respectively. This was attributable to an improvement in survival of infants at all birth weights but especially among those with very low birth weights, accounting for an estimated 83 to 85 per cent of the overall improvement. The birth weight distribution showed a slight worsening in the new and the old Länder with an increase in the proportion of those under 1500 g and, in the east, a 24 per cent increase in the proportion of high birth-weight infants of 4000 and more grams. Trends in postneonatal mortality revealed a worsening of about 32 per cent in the east from 1990 to 1991 followed by a decline of over 50 per cent up to 1997, leading to comparable mortality rates of 1.8 per thousand live births in the east and 2.0 in the west. While both parts experienced a decrease of 40 to 48 per cent in deaths from all diseases, the decline in deaths because of accidents and injuries was markedly higher in the new Länder although they are still exceeding the western rate by 3.7 per 100,000 live births in 1997.

CONCLUSIONS

Since unification, the two parts of Germany underwent a complex process that has led finally to convergence of parameters of infant health that are most likely to have been because of improvements in the quality of perinatal care. To improve infant mortality in Germany, policy measures should focus on preventive rather than curative measures as the proportion of very low birthweight babies is increasing in both parts of Germany.