Refugee women who come to Canada have greater risk of giving birth prematurely than non-refugee immigrants, a study by a St. Michael's Hospital researcher has found. Those risks are fueled by the fact that the preterm birth rate was 7.1 per cent among secondary refugees - those who spent more than six months in a transit country before arriving in Canada -compared to five per cent among secondary, non-refugee immigrants. These so-called "secondary refugees" also had a greater absolute risk of preterm birth than Canadian-born women (6.4 per cent).

"This suggests that experiences in countries before coming to Canada are not conducive to good health," said Dr. Susitha Wanigaratne, a researcher at St. Michael's Centre for Research on Inner City Health, who has a PhD in epidemiology.

Preterm or premature birth describes infants who are born before 37 weeks of gestation. Risk factors for include infections, malnutrition and stress - all very common among women living in refugee situations.

The higher risk found among secondary refugees was most apparent in very preterm deliveries, which occur at 22 to 31 weeks of gestation (1.2 per cent compared to 0.6 per cent among their non-refugee counterparts). The shorter the gestation length, the higher risk for the baby and associated health care issues.

Dr. Wanigaratne's research, published today in the Journal of Epidemiology and Community Health looked at Ontario immigration and hospital records housed at the Institute for Clinical Evaluative Sciences (ICES) from more than 120,000 births between 2002 and 2010, comparing births of refugee and non-refugee women. A total of 203 countries of origin were represented in the study.

"Overall, refugees had higher odds for preterm birth," said Dr. Wanigaratne. "However, when we examined primary immigrants and secondary immigrants separately, we found much greater odds of preterm birth among secondary refugee women."

As of 2013, the UN estimated about 3.15 million female refugees were living in long-term migration situations in a transition country, such as refugee camps. On average, refugees spent approximately 17 years in transition countries before finding a safe, permanent location.

"Our findings on the association between secondary refugees with preterm birth are extremely important from an international perspective given the current Syrian refugee crisis and other refugee crises," said Dr. Wanigaratne. "With women living in transition countries for potentially long periods of time, the risk for giving birth prematurely is amplified."

Preterm birth is a key indicator for the immediate and future health of babies. It is a leading predictor for perinatal death, feeding problems and respiratory complications at birth, as well as learning and cognitive disabilities later in life.

Dr. Wanigaratne said although some countries like Somalia have experienced large refugee crises, specific countries of origin did not explain the higher odds for preterm birth among secondary refugees. Rather, the findings suggested a universal risk for secondary refugee women, regardless of their country of origin.

"We believe some factors contributing to the higher risk may include long-term exposure to poor living conditions and stressors in transition countries including anxiety, racism, domestic or personal violence and major life events, such as a death in the family - to name a few," said Dr. Wanigaratne.

The researchers suggest implementing policies that work toward shortening the time refugee women spend in transition countries, emphasizing the need to move them to a safe place, quickly. In the meantime, improving access to health care and social services for refugees in transition countries may also be beneficial. In addition, health providers in Canada and other countries should also be sensitive to how the refugee migration journey may impact health.