Immigrant parents might be at greater risk of stillborn births, Ontario study suggests
April 14, 2015
By Jennifer Yang, Inside Belleville |
Nearly three million babies are born every year without any signs of life, a phenomenon that remains poorly understood by medical science. But a new study by Ontario researchers suggests that some parents who are immigrants might be at greater risk of having a stillborn birth.
The paper, published Tuesday by the Journal of Obstetrics and Gynaecology Canada, found a “significantly higher risk of stillbirth” among first-generation immigrant parents in Ontario — especially when both mom and dad were born in the same country where stillbirth rates are high.
Analyzing the top 20 countries from which couples immigrate to Ontario, researchers found parents from Nigeria, Portugal, Jamaica and Guyana had the greatest risk of stillbirth compared to Canadian-born couples. Parents born in China, the Philippines and Afghanistan had a slightly lower risk than Canadian couples.
“We’re trying to ask in the Canadian setting, where we have extreme diversity, whether there’s a difference between immigrants and non-immigrants in the risk of stillbirths,” said senior author, Dr. Joel Ray, a clinician scientist with St. Michael’s Hospital.
Ray hypothesized that certain immigrant couples could share genetic factors or environmental exposures that give them a higher risk of stillbirth. But he emphasized his study was still preliminary and there is no reason for foreign-born parents to be alarmed. More research is needed before conclusions can be drawn and “fortunately, stillbirths are rare and are still largely predicted by unknown factors rather than the origin of the couples.”
David Savitz, a professor of epidemiology, obstetrics and gynecology at Brown University, also cautioned that ethnicity alone cannot be blamed for stillbirths. Rather, it should be treated as a “marker” for some other factor, like economic status, which could be elevating the risk.
“(This paper) provides clues, and they can be very useful ones, but it’s a very early stage,” said Savitz, who was not involved with this study.
Globally, stillbirths are more common than people might assume. According to one estimate published in the Lancet, 2.6 million babies were stillborn in 2009. In Ontario, about one in every 200 viable pregnancies end in stillbirth.
In this study, Ray and his co-authors sifted through birth records for more than 1.1 million Ontario babies born between 2002 to 2011 after 20 weeks of gestation. Of those, 8,707 were stillborn but only 1,373 could be included in this study due to missing information in their records, including the parents’ countries of origin.
Using Canadian-born couples as a reference point, the researchers found the risk of stillbirth was much higher for immigrant couples — both those who come from the same country (1.32 times higher risk) and from different countries (1.34 times higher risk). These results took into account factors that might influence pregnancy outcomes, such as income, marital status and maternal age.
Researchers found similar results when aborted pregnancies were excluded or the analysis was limited to preemies or stillbirths caused by birth defects. But when they looked at couples where only the mother was an immigrant — and the father Canadian-born — the risk was lower, “suggesting that paternal country of origin may influence the risk of stillbirth.”
“A plausible explanation may be that immigrant couples have less access to prenatal care services than when one partner is Canadian-born,” the study said.
To Savitz, this study’s greatest weakness was that “the vast majority” of Ontario stillbirths could not be included due to missing data, so it doesn’t represent the full picture.
But like Ray, he views this paper as just another step toward solving that larger question: why do some babies die before they are even born?
“We don’t know the meaning yet,” Savitz said. “You keep generating these glimpses of information and hopefully down the road, we can put it together.”