4102.0 - Australian Social Trends, 2002
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 09/05/2002
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Mortality and Morbidity: Infant mortality
Trends in infant mortality Over the 20th century, the rate of infant deaths decreased from 103 deaths per 1,000 live births in 1900 to 5.2 deaths per 1,000 live births in 2000. The dramatic decline in the infant mortality rate during the first half of the century was linked to improvements in public sanitation and health education. In the 1940s, the development of vaccines and the ensuing programs of mass vaccination, along with effective use of antibiotics, resulted in further gains. These measures removed much of the earlier volatility in the infant mortality rate caused by outbreaks of infectious diseases. The more modest declines in the second half of the century were largely due to improved medical technology and education campaigns about the importance of immunisation;2 and most recently, in the case of Sudden Infant Death Syndrome (SIDS), infant sleeping position.3 Improvements in neonatal intensive care in the 1970s also played a major role in the continued decline in infant mortality in the latter part of the century. Infant deaths are commonly divided into those which occur within the first 28 days of life (called the neonatal period) and those which occur on or after the 28th day but in the first year of life (called the postneonatal period). Improvements in infant mortality varied for babies of different age groups over the century. Until the 1940s, the decline in the infant mortality rate was mostly due to a rapid decline in postneonatal deaths. In contrast, after World War II, the decline was greater for neonatal deaths than for older babies. Infant mortality rates are higher among boys than girls for almost all leading causes of death. This difference is largely biological in origin.4 Between 1980 and 2000, the infant mortality rate for boys was, on average, 27% higher than that for girls. INFANT MORTALITY RATE(a) (a) Per 1,000 live births. Source: Deaths, Australia, 2000 (ABS cat. no. 3302.0). Neonatal mortality The death rate for babies aged under 28 days continued to decline rapidly over the last two decades of the 20th century. Between 1980 and 2000, the neonatal mortality rate declined from 7.1 to 3.5 deaths per 1,000 live births. The rate of decline was similar for boys and girls. In 1997-2000, two major groups of causes accounted for 95% of neonatal deaths - conditions originating in the perinatal period (pregnancy and the first 28 days of life) (64%), and congenital malformations (31%). Conditions which originate in the perinatal period include causes that relate to pregnancy, fetal growth, labour and delivery. Congenital malformations are conditions present at birth that are either hereditary or originating from pregnancy, including deformities and chromosomal abnormalities. NEONATAL DEATHS
Source: ABS Causes of Death collection. Over the last decade of the 20th century, the neonatal death rate from conditions originating in the perinatal period declined by 26%, from 3.1 deaths per 1,000 live births in 1987-1990 to 2.3 deaths per 1,000 live births in 1997-2000. In 1997-2000, 56% of neonatal deaths from conditions originating in the perinatal period were due to maternal factors and complications of pregnancy, labour and delivery (36% of all neonatal deaths). Because of changes in the classification of causes of death, a comparable figure is not available for 1987-1990. The two other common types of conditions originating in the perinatal period were hypoxia, birth asphyxia and other respiratory conditions (accounting for 12% of neonatal deaths in 1997-2000), and disorders relating to length of gestation and fetal growth (accounting for 4% of deaths). Both types of conditions made up a greater proportion of neonatal deaths a decade earlier (27% and 19% respectively in 1987-1990). Over the same period, there was a slight increase in the proportion of deaths from conditions which originate in the perinatal period which were not identified. Between 1987-1990 and 1997-2000, the neonatal death rate for congenital malformations declined from 1.6 to 1.1 deaths per 1,000 live births, partly due to improved screening methods to detect such conditions (including amniocentesis and ultrasound) and greater awareness of preventative measures during pregnancy. NEONATAL MORTALITY RATE(a) (a) Rate per 1,000 live births. Source: ABS Causes of Death collection. Postneonatal mortality Between 1980 and 2000, the mortality rate for babies aged 28 days and under one year declined by 53% from 3.6 to 1.7 deaths per 1,000 live births. The rate of decline was similar for boys and girls. Babies who die after the first 28 days of life were likely to die from a greater range of causes than those who die in their first four weeks of life. Congenital malformations and conditions originating in the perinatal period were again among the more common causes of postneonatal deaths, accounting for 21% and 12% of deaths respectively in 1997-2000. However, the most commonly cited group of causes were symptoms, signs and abnormal clinical and laboratory findings not elsewhere classified. This group of causes accounted for a third of postneonatal deaths in 1997-2000, the bulk of them (30% of all postneonatal deaths) caused by Sudden Infant Death Syndrome (SIDS).
Between 1987-1990 and 1997-2000, the postneonatal death rate for SIDS declined from 1.8 to 0.5 deaths per 1,000 live births. Proportionally, this equated to a decrease from 54% to 30% of all postneonatal deaths. The decrease in death rate for SIDS occurred following the introduction of a national health educational campaign in 1990. The campaign highlighted the risk factors which are associated with SIDS such as sleeping position, feeding practices and exposure to passive smoking.3 POSTNEONATAL DEATHS
Source: ABS Causes of Deaths Collection. The death rates for conditions originating in the perinatal period, and for congenital malformations declined to 0.2 and 0.4 deaths per 1,000 live births respectively between 1987-1990 and 1997-2000. However, these two groups of causes accounted for a greater proportion of postneonatal deaths in 1997-2000 than they did a decade earlier, as a result of the greater gains in reducing deaths caused by SIDS and the improved survival of babies with these conditions beyond the first 28 days of life. POSTNEONATAL MORTALITY RATE(a) (a) Rate per 1,000 live births. Source: ABS Causes of Death collection. State and Territory differences There is some variation in infant mortality rates across States and Territories. In 2000, the rates ranged from 4.2 deaths per 1,000 live births in the ACT to 11.7 deaths per 1,000 live births in the Northern Territory. The notably higher infant mortality rate in the Northern Territory reflects the higher proportion of Indigenous babies born in the Northern Territory. Overall, the infant mortality rate for the Indigenous population is much higher than for the total Australian population (13.5 deaths per 1,000 live births compared with 5.3 deaths per 1,000 live births in 1998-2000). For more information on Indigenous mortality rates see Australian Social Trends 2002, Mortality of Aboriginal and Torres Strait Islander peoples. STATE/TERRITORY INFANT MORTALITY RATES(a)
Source: Deaths, Australia, 2000 (ABS Cat. no. 3302.0). Between 1980 and 2000, the infant mortality rate for Australia decreased by 51%, from 10.7 to 5.2 deaths per 1,000 live births. Decreases varied across States and Territories with Western Australia and Victoria experiencing the greatest declines over the period - 63% and 55% to 4.3 and 4.5 deaths per 1,000 live births respectively in 2000. While infant mortality rates in Tasmania and the Australian Capital Territory have decreased in line with the national trend, they have shown more variability from year to year due to the small numbers of infant deaths.
Endnotes 1 United Nations, 1988 Mortality of children under age 5: World Estimates and projections 1950-2025, United Nations, New York. 2 Stanley, F. J. 2001, 'Child health since Federation', in Year Book Australia 2001, ABS cat. no. 1301.0, pp. 368-400, Ausinfo, Canberra. 3 SIDS Australia Online, <URL: http://www. sidsaustralia.org.au/> (accessed 25/10/2001). 4 Australian Bureau of Statistics 1998, Causes of Infant and Child Deaths, 1982-1996, cat. no. 4398.0, ABS, Canberra.
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