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Hospital Admissions and Mortality with a Social Gradient in Children | Infant Mortality |
Injuries Arising from the Assault, Neglect or Maltreatment of Children |
Ambulatory Sensitive Hospitalisations | Appendices

Infant Mortality

Introduction

Infant mortality is often used as a barometer of the social wellbeing of a country [1]. New Zealand's infant mortality rates are middling by international standards, being lower than those of the USA and some Eastern European countries, but higher than those of Central and Northern Europe [2]. Despite this, mortality during the first year of life in New Zealand remains much higher than at any other point during childhood or adolescence. In the year to March 2008, a total of 330 New Zealand infants died prior to their first birthday [3].

Despite these relatively high numbers, New Zealand's infant mortality rates have declined during the past 40 years, with rates falling from 18.2 per 1,000 in 1968, to 5.3 per 1,000 in March 2008 [3]. While infant mortality rates are generally higher for Pacific > Māori > European / Other babies, males, and those in the most deprived areas [4], total infant mortality rates are of limited utility in guiding population health interventions, as the causes of mortality differ markedly with the age of the infant. During the neonatal period (birth-28 days) extreme prematurity, congenital anomalies and intrauterine / birth asphyxia are the leading causes of mortality, while in the post neonatal period (29 -364 days) SIDS and congenital anomalies make the greatest contribution [5]. Thus any interventions aimed at reducing New Zealand's infant mortality rates must, in the first instance, be based on an understanding of their component causes.

This indicator uses information from the National Mortality Collection to review neonatal, post neonatal and infant mortality since 1990.

 

New Zealand Distribution and Trends

New Zealand Trends
In New Zealand, while neonatal and post neonatal mortality both declined during the early-mid 1990s, declines during the 2000s were less marked. During the 2000s, neonatal mortality exceeded post neonatal mortality (Figure 1).

 

Figure 1: Total, Neonatal and Post Neonatal Mortality, New Zealand 1990-2006

Source: Numerator National Mortality Collection; Denominator Birth Registration Dataset

 

Figure 2:Total, Neonatal and Post Neonatal Mortality by Ethnicity, New Zealand 1996-06

Source: Numerator National Mortality Collection; Denominator Birth Registration Dataset; Ethnicity is Level 1 Prioritized

New Zealand Trends by Ethnicity
In New Zealand during the late 1990s, neonatal mortality was generally higher for Pacific and Māori > European > Asian infants, although ethnic differences were less consistent during the 2000s. In contrast, post neonatal mortality was higher for Māori > Pacific > European and Asian infants throughout 1996-2006 (Figure 2).

Distribution by Cause
In New Zealand during 2002-2006, extreme prematurity and congenital anomalies were the leading causes of neonatal mortality, although intrauterine / birth asphyxia also made a significant contribution. In contrast, SUDI was the leading cause of post-neonatal mortality, followed by congenital anomalies (Table 1).

Table 1. Neonatal and Post Neonatal Mortality by Cause, New Zealand 2002-2006

Source: Numerator National Mortality Collection; Denominator Birth Registration Dataset

 

Distribution by Ethnicity, Gender and NZDep Deprivation
In New Zealand during 2002-2006, neonatal and post neonatal mortality were both significantly higher for Pacific and Māori > European and Asian infants, males and those in more deprived areas, while SUDI was significantly higher for Māori > Pacific > European and Asian infants, and those in average to more deprived areas (Table 2).

Table 2. Risk Factors for Neonatal and Post Neonatal Mortality, and Sudden Unexpected Death in Infancy (SUDI), New Zealand 2002-2006

Source: Numerator National Mortality Collection; Denominator Birth Registration Dataset; Rates are per 100,000, Rate Ratios are Unadjusted, Ethnicity is Level 1 Prioritised. SUDI is neonatal AND post neonatal.

Summary

In New Zealand, while neonatal and post neonatal mortality both declined during the early-mid 1990s, declines during the 2000s were less marked. When broken down by ethnicity, neonatal mortality was higher for Pacific and Māori > European > Asian infants during the late 1990s, although ethnic differences were less consistent during the 2000s. In contrast, post neonatal mortality was higher for Māori > Pacific > European and Asian infants throughout 1996-2006.

When broken down by cause, extreme prematurity and congenital anomalies were the leading causes of neonatal mortality in New Zealand during 2002-2006. In contrast, SUDI was the leading cause of post-neonatal mortality, followed by congenital anomalies. During this period, neonatal and post neonatal mortality were both significantly higher for Pacific and Māori > European and Asian infants, males and those in more deprived areas, while SUDI was significantly higher for Māori > Pacific > European and Asian infants, and those in average to more deprived areas.

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References

Gorski, P., Perinatal Outcome and Social the Contract - Interrelationships Between Health and Humanity. Journal of Perinatology, 1998. 18(4): p. 297 - 301.

2. OECD Social Policy Division (2008) OECD Family Database: CO1 Infant Mortality. OECD Health at a Glance 2008.

3. Statistics New Zealand (2008) Births and Deaths: March 2008 Quarter. Hot Off the Press, 1-13.

4. Public Health Intelligence, An Indication of New Zealander's Health 2004. 2004, Ministry of Health: Wellington. p. 52-54.

5. Craig, E., et al., Monitoring the Health of New Zealand Children and Young People: Indicator Handbook. 2007, Paediatric Society of New Zealand & New Zealand Child and Youth Epidemiology Service: Auckland.