A Health Surveillance Update on Canadian Children and Youth

Infant Mortality

With the exception of Japan, Canada has had the most dramatic decline in infant mortality rates in the past 35 years.

Infant mortality rate is often used as an indicator of a country's state of health development. Infant mortality refers to the death of a live born infant within the first year of life. Rates of infant mortality are usually based on the number of infant deaths per 1,000 live births in any given year, but are sometimes based on the number of infant deaths per 1,000 population less than one year old. Two related terms used to describe infant mortality are neonatal death - the death of an infant under 28 days of age - and post-neonatal death - the death of an infant between 28 days and 1 year of age.

In 1996, 2,051 infants in Canada died before their first birthday.⁽¹⁾ Of these deaths, 1,441 (70%) occurred in the neonatal period and 610 (30%) in the post-neonatal period. The two leading causes of neonatal death were conditions originating in the perinatal period and congenital anomalies. Conditions originating in the perinatal period, which include respiratory distress syndrome, short gestation and low birth weight, accounted for 62% of neonatal deaths. Congenital anomalies accounted for 30% of neonatal deaths. The two leading causes of post-neonatal death were sudden infant death syndrome (SIDS) and congenital anomalies, accounting for 26% and 23% of post-neonatal deaths respectively.

With the exception of Japan, Canada has had the most dramatic decline in infant mortality rates in the past 35 years. In 1996, the infant mortality rate in Canada was 5.6 per 1,000 live births compared with a rate of 27.3 per 1,000 live births in 1960; it has decreased steadily since the early 1960s, tapering off somewhat in the mid-1980s. Figure 1 depicts the Canadian infant mortality rate from 1960 until 1996.

Source: Bureau of Reproductive and Child Health, LCDC, based on Statistics Canada data⁽¹⁾

Low birth weight is correlated with higher rates of mortality and morbidity among infants. Regional and temporal variations in the classification of live births weighing less than 1,500 g have been reported in the medical literature.^(2,3,4) Analyses of Canadian data have demonstrated that including live births weighing less than 500 g changes the infant mortality rates.^(4,5) From 1992 to 1993, the infant mortality rate, including all live births, increased from 6.1 to 6.3 per 1,000 live births. However, the exclusion of live births weighing less than 500 g resulted in a decreasing rate, from 5.6 to 5.4 per 1,000 live births. An increasing rate of live births weighing less than 500 g during this period, from 5.1 to 8.5 per 1,000 live births, explains this variation and highlights the importance of accounting for these extremely low birth weight infants in infant mortality analysis.

In comparison with infant mortality rates in other Organization for Economic Cooperation and Development (OECD) countries, Canada's rate of 5.6 per 1,000 live births is somewhat high.⁽⁶⁾ As depicted in Figure 2, in 1996, Japan, Finland and Sweden reported the lowest infant mortality rates at 3.8, 4.0 and 4.0 per 1,000 live births respectively; New Zealand and the United States reported the highest rates at 7.4 and 7.8 per 1,000 live births respectively.

Source: OECD Data, 1998, except Canada: Bureau of Reproductive and Child Health, LCDC^(1,6)

Data limitations
International differences in infant mortality rates must be interpreted with caution as there are significant international variations in clinical practice and in the way live births are classified.^(2,3) Furthermore, even in Canada, there is a lack of consistency in handling live births weighing less than 500 g for infant mortality calculations.

Summary
Since the early 1960s, reductions in infant mortality rates in Canada have been dramatic and encouraging. However, there is still room for improvement, as other OECD countries have lower infant mortality rates.

Unless referenced otherwise, infant mortality statistics are the product of the Bureau of Reproductive and Child Health, LCDC.⁽¹⁾

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