As Canada’s immigration grows, a new study suggests babies born to immigrant parents are at an increased risk of complications at birth.
The rate of stillbirth, which is fetal death occurring after 20 weeks of gestation or at a birth weight of at least 500 grams, was higher among immigrant parents when compared to native Canadians, according to research published in the Canadian Medical Association Journal (CMAJ) Tuesday.
The likelihood of preterm birth, when the baby is born before 37 weeks of pregnancy are completed, was also higher for immigrant parents admitted into Canada on an economic and family reunification basis, as well as for refugees.
Researchers at McGill University and Université de Montréal looked at Statistics Canada data of nearly eight million Canadian births – out of which 21 per cent were to immigrants – over a 25-year period between 1993 and 2017.
“We found differences in outcomes not only between Canadian-born parents and immigrants, but also by the admission category among immigrants,” said Seungmi Yang, study co-author and associate professor in the department of epidemiology, biostatistics and occupational health at McGill University, in an interview with Global News.
“Births to immigrant parents had increased risk of several but not all adverse outcomes,” the authors wrote in the study.
While the risk of small for gestational age (SGA) birth was higher among the immigrant population, there was a lower risk of large for gestational age (LGA) birth compared to Canadian-born parents, the study found.
SGA birth is when the baby is born with a birth weight below the 10th percentile among an infant population of the same sex and gestational age. LGA birth is defined as the birth weight above the 90th percentile.
The rate of infant death that happened within the first year of the baby’s life was lower among immigrants as well when compared to native Canadian parents.
Birth risk factors
The risk levels for stillbirth and preterm birth were lowest for economic-class immigrants and highest for refugees, which is consistent with other previous studies, the authors said.
This is likely because “economic-class immigrants use more primary care services than refugees and family-class immigrants, and refugees are less likely to have a regular physician than non-refugees,” they noted.
Yang said given the differences observed in outcomes within the immigrant population, the admissions category could be a “meaningful characteristic” that can help provide more tailored care to different groups.
“We just want to stress that immigrants are not a single group as commonly considered, so sub-populations are important,” Yang said.
As for the increased risk of preterm birth for immigrants compared to Canadian-born parents, systemic racism could be a factor, the authors said.
Smoking, being underweight, and intrauterine infection are other risk factors for early preterm birth, they said.
Another recent CMAJ study found that maternal obesity was associated with an increased likelihood of stillbirth.
Overall, babies in Canada are getting smaller, data shows.
A Statistics Canada study from January 2022 found that the mean birth weight for all births decreased from 3,442 grams in 2000, to 3,367 grams in 2016, while SGA birth increased from 7.2 per cent in 2000 to 8.0 per cent in 2016.
This trend can partly be explained by important risk factors such as an increase in maternal and paternal immigration, delayed childbirth, an increase in first-time mothers or an increase in non-married women, StatCan said.
Immigration makes up nearly a quarter (23 per cent) of the Canadian population, according to the 2021 census data.
In 2023, most of Canada’s 3.2 per cent population growth rate – which was the highest since 1957 – stemmed from temporary immigration, Statistics Canada said in a report last week.
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