La symptomatologie dépressive prénatale : une étude comparative des femmes canadiennes et immigrantes à Montréal

Background: Approximately 20% of childbearing women present a high risk of antenatal depression. Immigrant women present high depressive symptoms during pregnancy, the early post-partum period and as mothers of young children. While ethnic disparities in depressive symptomatology during pregnancy have been described abroad, the combination of length of stay and region of origin is rarely assessed in studies of immigrant health in Canada. Also, studies of pregnant immigrant women often have a sample size which is insufficient to disentangle the effect that region of origin and length of stay has on mental health.  Moreover, in Canada, almost one in five women is an immigrant, but little is known about immigrant women’s mental health during pregnancy, their levels of exposure to recognized risk factors for antenatal depression, or how their exposure and vulnerability to these risks compares to that of Canadian-born pregnant women. There is also growing awareness that the immigration process may be accompanied by numerous challenges that increase the risk for intimate partner violence. Nevertheless, existing evidence in the literature is conflicting, especially with regard to the type of violence assessed, the extent to which specific immigrant minority populations are considered, and the inclusion of mental health status.  Objectives: First, we compared mental health of immigrant and Canadian native-born women during pregnancy according to length of stay and region of origin, and we assessed the role of economics and social support in antenatal depressive symptoms. Second, we examined the distribution of contextual risk factors for antenatal depressive symptoms according to immigrant status and the length of stay in Canada, and assessed the association between these risk factors and antenatal depressive symptoms for Canadian-born and immigrant women, and then compared the vulnerability of Canadian-born and immigrant women to risk factors in relation to antenatal depressive symptoms. Third, we described the prevalence of violence during pregnancy, and examined the association between the experience of violence since the beginning of pregnancy and the prevalence of antenatal depressive symptoms, taking into account immigrant status.   Methods: Data originated from the Montreal study on socioeconomic differences in prematurity. Women were recruited at routine ultrasound examinations (16-20 weeks), at antenatal blood sampling (8-12 weeks), or in antenatal care clinics. Using the Center for Epidemiologic Studies Depression scale, 3834 Canadian-born and 1495 immigrant women were evaluated for depression at 24-26 weeks of pregnancy. Levels of exposure to the selected risk factors according to immigrant status and length of stay were assessed using the Chi-square-test or the t-test. The Abuse Assessment Screen scale was used to determine the frequency and severity of violence since the beginning of pregnancy. Relationship with abuser was also considered. All measures of association were assessed using logistic regression. Multiplicative interaction terms were constructed between each of the risk factors and immigrant status to reveal differential vulnerability between Canadian-born and immigrant women.  Results: Prevalence of antenatal depressive symptoms (CES-D >=16 points) was higher in immigrants (32% [29.6- 34.4]) than in Canadian-born women (22.8 % IC 95% [21.4- 24.1]). Immigrant women had higher depressive symptomatology independently of time since immigration. Region of origin was a strong predictor of depressive symptomatology: women from the Caribbean (45%), South Asia (43%), Maghreb (42%), Sub-Saharan Africa (39%) and Latin America (33%) had the highest prevalence of depressive symptomatology compared to Canadian-born women (22%) and women form East Asia the lowest (17%). The higher depression odds in immigrant women are attenuated after adjustment for lack of social support and money for basic needs. Time trends of depressive symptoms varied across origins. In relation to length of stay, depressive symptoms increased (European, Southeast Asian), decreased (Maghrebian, Sub-Saharan African, Middle Eastern, East Asian) or fluctuated (Latin American, Caribbean). Immigrant women were significantly more exposed than Canadian-born women to adverse contextual risk factors such as high marital strain, lack of social support, poverty, and crowding. At the same level of exposure to risk factors, Canadian-born women presented higher vulnerability to antenatal depressive symptoms when lacking social support (OR= 4.14 IC95% [2.69;6.37] ) while immigrant women presented higher vulnerability to antenatal depressive symptoms  when lacking money for basic needs (OR=2.98 IC95% [2.06;4.32]). Threats were the most frequent type of violence with 63% happening more than once. Long-term immigrant women reported the highest prevalence of all types of violence (7,7%). Intimate partner violence was most frequently reported (15%) among the poorest pregnant women. Strong associations exist between more than one episode of abuse and depression (POR= 5,21 [3,73; 7,23], and intimate partner violence and depression [POR=5,81 [4,19;8,08]. Immigrant status did not change the associations between violence and depression.  Conclusion: The observed high frequencies of depressive symptoms highlight the need to evaluate the effectiveness of preventive interventions against antenatal depression. Depression in minority pregnant women deserves more attention, independently of their length of stay in Canada. Important risk factor exposure inequalities exist between Canadian-born and immigrant pregnant women. Social support interventions favouring integration and poverty reduction could reduce the risk of antenatal depression. Violence against pregnant women is not rare in Canada and it is associated with antenatal depressive symptoms. These findings support future development of perinatal screening for violence, follow-up and a culturally sensitive referral system.

Keyphrases: Pregnancy, Depression, Immigrant Status, Region of Origin