Women in poor Toronto districts more likely to deliver preterm babies: study

From EndCanadianPoverty.ca

• Date: October 3rd, 2007
• Source: CBC News
• Link to article: Women in poor Toronto districts more likely to deliver preterm babies: study

"Where and when a woman arrives in Toronto can play a big part in the delivery and health of her baby, according to a study released Tuesday by Statistics Canada.

Though newly arrived immigrants are on par with more affluent Torontonians in terms of birth outcomes, longer-term residents in poorer neighbourhoods have an increased risk of preterm birth and other delivery complications, the report finds.

Among long-term residents, those in neighbourhoods with the lowest income had a 34 per cent greater risk of preterm birth, compared with mothers in neighbourhoods with the highest income. This trend did not apply to recent immigrants.Among long-term residents, those in neighbourhoods with the lowest income had a 34 per cent greater risk of preterm birth, compared with mothers in neighbourhoods with the highest income. This trend did not apply to recent immigrants.

The study examined 143,030 single live births to mothers in Toronto between April 1996 and March 2001. It divided neighbourhoods into five income groups, from the highest one-fifth to the lowest, based on the proportion of their population below Statistics Canada's low-income cutoff.

The study defined premature birth as a birthweight of two pounds three ounces to five pounds eight ounces and a pregnancy term of 28 to 37 completed weeks. Low birthweight was defined as less than five pounds eight ounces.

Long-term, poor residents most at risk

Among long-term residents, those in neighbourhoods with the lowest income had a 34 per cent greater risk of preterm birth, compared with mothers in neighbourhoods with the highest income. This trend did not apply to recent immigrants.

Compared with mothers in the most affluent neighbourhood, those from the poorest were more likely to be younger than 20 and to have had at least one illness during pregnancy. They also had 25 per cent higher odds of preterm birth, 26 per cent higher odds of low birthweight and 53 per cent higher odds off full-term low birthweight.

"Longer-term residents in low-income neighbourhoods were clearly the subgroup experiencing the highest risk of adverse birth outcomes, probably because of the influence of lasting socio-economic disadvantage," reads the report.

Babies born to mothers who had recently immigrated to Toronto accounted for 32.5 per cent of all births in the study. These were more likely to be low birthweight than longer-term residents and to be full-term low birthweight.

Researchers speculate that this might be due to a "healthy migrant" effect among immigrant women that makes them less prone to the conditions that can cause preterm birth, such as genito-urinary infection, pregnancy-induced hypertension, incompetent cervix (a condition in which the cervix weakens and can lead to early delivery) and placental abruption, the premature separation of the placenta before childbirth.

Recent immigrants are also less likely to be exposed to smoke and alcohol, the authors theorize, an exposure that increases the longer a person lives in a poorer neighbourhood."