Stillbirth and infant mortality in Aboriginal communities in Quebec
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by Nicolas L. Gilbert, Nathalie Auger and Michael Tjepkema
Several studies have shown that infant mortality and stillbirth rates are higher among First Nations and Inuit people than in the rest of the Canadian population.Note 1-4 In these studies, Aboriginal people were identified on the basis of residence in an area with a large percentage of Aboriginal people, census data, self-identification on birth records (British Columbia), or mother tongue of the mother (Quebec).
However, these studies do not distinguish First Nations people who live on reserves. It is useful to determine the health status of First Nations people living on reserves, whose socio-economic conditions are often more precarious than those of the rest of the population.Note 5 In addition, health services on reserves are managed under a separate health system. Health Canada provides funding for prevention and health promotion as well as for home and community care services for people living on reserves. Health Canada is also responsible for primary health care on remote reserves, whereas the responsibility is provincial for the rest of the population. Determining the health status of the on-reserve population would facilitate planning of health programs. Identifying members of this population based on language has the disadvantage of excluding Aboriginal people who adopted English or French as their home language.
This analysis was undertaken to measure stillbirth and infant mortality rates of Aboriginal people in Quebec, in particular First Nations people living on reserves, and to compare them with rates for non-Aboriginal people in that province.
Data and methods
Data on live births and stillbirths in Quebec from 1989 to 2008 were extracted from Statistics Canada’s Infant Birth-Death Linked File, which was created by linking the death records of infants younger than one year of age with birth records.Note 6 At the time of this study, 2008 was the most recent year for which record linkage was completed.
Births that took place in Aboriginal communities were identified by postal code. The validity of the postal codes was verified using Statistics Canada’s Postal Code Conversion File Plus (PCCF+).Note 7 Only records containing a valid postal code for residential buildings (97.3% of the total) were retained.
Using the PCCF+ program, a list of postal codes corresponding to First Nations Reserves, Cree or Naskapi communities and Inuit communities was established by type of census subdivision. The Cree and Naskapi were processed separately from other First Nations people because they differ in two respects:
- Under the 1975 James Bay and Northern Quebec Agreement, Quebec’s Cree and Naskapi communities are no longer reserves within the meaning of the Indian Act. Health Canada does not fund primary care for this population, although it provides services and programs supplementing health services provided by the province.
- Compensation paid by the Quebec government for use of hydroelectric resources located on their territory has changed their socio-economic status.
Because 11 First Nations reserves in Quebec share postal codes with a neighbouring non-Aboriginal community, these Aboriginal communities cannot be identified using the postal codes. These communities include: Gesgapegiag, Timiskaming, Eagle Village, Ekuanitshit, Natashquan, Essipit, Matimekush-Lac John, Winneway, Kanesatake and Pakuashipi. Therefore, two separate variables were created to classify Aboriginal communities: one including shared postal codes with Aboriginal communities, and another including shared postal codes with non-Aboriginal communities.
The following outcomes were analyzed:
- Stillbirths of fetuses weighing 500 grams or more (after exclusion of pregnancy termination);
- Neonatal deaths (0 to 27 days after birth);
- Post-neonatal deaths (28 to 364 days after birth);
- Infant deaths (sum of neonatal and post-neonatal deaths).
The following variables, obtained from birth records, were included in the analysis:
- Mothers’ age (10 to 19, 20 to 34, and 35 or older), because infant mortalityNote 8 and stillbirth ratesNote 9 are higher for children of mothers younger than 20 and 35 or older;
- Mothers’ years of education (9 or less, 10 to 12, and 13 or more), because less education is associated with higher stillbirth and infant mortality ratesNote 10;
- Multiple births, a risk factor for stillbirth and infant mortalityNote 11;
- Year of birth, grouped by five-year period, to account for the decline in infant mortality during the 1990s and 2000s.Note 8
- community size and the influence of metropolitan zones (a measure of rural isolation), combined into one variable;
- north-south gradient.
Mortality rates for the different outcomes were calculated. Associations between the outcomes and risk factors (Aboriginal status, mothers’ age and education, multiple birth, north-south gradient, size and isolation of communities) were examined. Unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression models.
In accordance with Statistics Canada’s rules on disclosure, counts were rounded to the nearest 10, and rates were calculated based on rounded values. However, odds ratios were calculated based on exact numbers.
A total of 1,620,270 live births and 5,560 stillbirths were included in the analysis (Table 1). Of the live births, 8,100 were linked to death records. The number of births on First Nations reserves, including reserves with a shared postal code, was estimated at 16,240. When births occurring on reserves with shared postal codes were excluded, the number declined to 12,170. The numbers of births in Cree and Naskapi communities and Inuit communities were 6,860 and 5,350, respectively. Aboriginal mothers were substantially younger and had less education than non-Aboriginal mothers (Table 2).
For most outcomes, rates and odds ratios were not substantially different if communities with shared postal codes were included as non-Aboriginal, compared with including shared postal codes as reserves. Consequently, only the results based on the former approach are shown in Tables 2 to 6. Post-neonatal mortality was the only outcome for which the approach used changed the results noticeably.
Stillbirth rates for Aboriginal people living on First Nations reserves, in Cree and Naskapi communities and in Inuit communities were significantly higher than for non-Aboriginal people, but differences were not statistically significant after adjustment for maternal characteristics, multiple birth and geographic isolation (Table 3).
Infant mortality was higher for all Aboriginal groups. However, on First Nations reserves, the difference disappeared after adjustment for maternal characteristics, multiple birth and geographic isolation (Table 4).
Neonatal mortality was significantly higher for Inuit than for non-Aboriginal people, but there was no significant difference in neonatal mortality emerged between First Nations and non-Aboriginal people (Table 5).
Finally, post-neonatal mortality was significantly higher for all Aboriginal groups than for non-Aboriginal people. Excess mortality remained significant after adjustment (Table 6). The difference between First Nations reserves and non-Aboriginal communities was greater if shared postal codes were included with non-Aboriginal communities (adjusted OR: 1.79; 95% CI: 1.29 – 2.47) than if they were included with reserves (adjusted OR: 1.57; 95% CI: 1.16 – 2.13).
The differences in perinatal health between Aboriginal and non-Aboriginal people in Quebec are already known.Note 1-4 This study sheds new light by describing the perinatal health status of First Nations people living on reserves and in Cree and Naskapi communities, and comparing them with non-Aboriginal people.
The significantly higher rates of stillbirth, neonatal mortality and post-neonatal mortality before adjustment (for mothers’ age and education, size and isolation of community and period) indicate that Aboriginal communities are disadvantaged in relation to the rest of the province’s population. The significantly higher rates of post-neonatal mortality among Aboriginal people, and of stillbirth among Inuit, even after adjustment, show that regardless of differences in mothers’ age and education, a gap persists. Some behaviours associated with stillbirth or infant mortality are also associated with mothers’ age and education, including smoking during pregnancy, which is a risk factor, and breastfeeding, a protective factor.Note 14
First Nations people living on reserves had a higher stillbirth rate but lower neonatal mortality rate than non-Aboriginal people. It is possible that the apparently low neonatal mortality among First Nations people reflects under-registration of non-viable newborns. This phenomenon has been observed in OntarioNote 15 and might exist in some health care institutions in other provinces.
Excess mortality associated with stillbirth in Aboriginal communities was attenuated and ceased to be significant after adjustment for age, mother’s education and the size and isolation of communities, suggesting that the excess was partly due to these factors.
Post-neonatal mortality was also higher among Aboriginal people than in the rest of the population, and the differences remained statistically significant after adjustment. In fact, post-neonatal mortality is the outcome for which the gap between Aboriginal and non-Aboriginal people was greatest. Other studies have found differences between socio-economic classes were greater for post-neonatal mortality than for stillbirths and neonatal mortality.Note 8,Note 16 The small number of events (approximately 100 infant deaths for on-reserve populations, 60 for Cree and Naskapi, and 110 for Inuit) made it difficult to examine specific causes of mortality.
In the absence of data on behaviours and other individual risk and protective factors, it was impossible to identify possible causes of the differences observed in this study. However, several known risk factors are more prevalent among Aboriginal people than in the rest of the population. For example, Inuit and First Nations women in Quebec smoke more than other women in the provinceNote 17,Note 18; the rate of macosomia (birth weight exceeding 4,000 grams) is higher for First Nations people than for non-Aboriginal peopleNote 13,Note 19; and the prematurity rate is higher for Inuit.Note 20 Furthermore, the unfavourable socio-economic conditions that prevail in a number of communities may be associated with other risk factors that are not captured in vital statistics and health surveys.
The main limitation of this study is the use of postal codes to identify Aboriginal people, which does not precisely distinguish between Aboriginal and non-Aboriginal people living in the same community. Other limitations are the lack of information on stillbirths under 500 grams (for which registration is not required), possible under-registration of neonatal deaths, and the small number of events with associated requirement to round numbers, which made it impossible to study mortality rates by cause of death. Finally, use of vital statistics data limited the analysis to data collected during birth and death registration, and behavioural factors such as breastfeeding and smoking could not be taken into account.
Stillbirth and post-neonatal mortality are higher on First Nations reserves, in Cree and Naskapi communities, and in Inuit communities than in the rest of the Quebec population. Neonatal mortality is also higher among Inuit. In the case of post-neonatal mortality, the difference between Aboriginal and non-Aboriginal people persisted after adjustment for socio-demographic differences (mothers’ age and education), which indicates that other mechanisms may contribute to the observed differences.
The authors thank Laurie St-Onge for assistance in developing postal code lists, Russell Wilkins for invaluable advice, and Christine Fogl and Sylvie Aubuchon for reading and commenting on a preliminary version of this article.