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Gestational Diabetes Among Immigrant Women

Urquia, Marcelo; Glazier, Richard H.; Berger, Howard; Ying, Ivan; De Souza, Leanne; Ray, Joel G.

doi: 10.1097/EDE.0b013e31823199ee
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Centre for Research on Inner City Health; St. Michael's Hospital; Institute for Clinical Evaluative Sciences; Toronto, ON (Urquia)

Institute for Clinical Evaluative Sciences; Centre for Research on Inner City Health; Department of Family and Community Medicine; St. Michael's Hospital,; University of Toronto; Toronto, ON, Canada (Glazier)

Department of Obstetrics and Gynecology; St. Michael's Hospital; University of Toronto; Toronto, ON, Canada (Berger)

Department of Medicine; Schulich School of Medicine and Dentistry; London, ON, Canada (Ying)

Department of Obstetrics and Gynecology; St. Michael's Hospital; University of Toronto; Toronto, ON, Canada (De Souza)

Departments of Medicine and of Obstetrics and Gynecology; St. Michael's Hospital; Institute for Clinical Evaluative Sciences; University of Toronto; Toronto, ON, Canada; rayj@smh.ca (Ray)

Supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC).

Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).

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To the Editor:

Gestational diabetes mellitus is more common among certain non-White ethnic groups1; however, classifying these women as “African American,” “Asian,” or “Hispanic”2 fails to appreciate the broader ethnic fabric of many countries. We compared the risk of gestational diabetes mellitus among diverse groups of women who had immigrated to Canada compared with Canadian-born women.

Using the federal Landed Immigrant Data System database, we identified a population-based cohort of women who were new immigrants to Ontario between 1985 and 2000. This data source has records for every permanent legal immigrant to Canada who arrived after 1984. As described elsewhere,3 these data have been linked to the Canadian Institute for Health Information Discharge Abstracts Database, thereby capturing all subsequent delivery hospitalizations in Ontario between 1 April 2002 and 31 March 2009. A diagnosis of gestational diabetes mellitus was captured at the time of any live birth or stillbirth delivery, based on an ICD-10-CA code for gestational diabetes mellitus, while excluding those with an ICD-10-CA diagnosis of prepregnancy diabetes.

The rate and odds ratio (OR) of gestational diabetes mellitus were determined according to maternal World region of birth (www.unicef.org/infobycountry/index.html). ORs were adjusted for variables listed in the footnote of the Table. A woman could contribute more than one delivery to the dataset. The study was approved by the Ethics Review Board of Sunnybrook and Women's College Health Sciences Centre.

Table

Table

Among 792,314 delivery records, 21,439 (3%) had missing or invalid information, leaving a final sample of 770,875 consecutive deliveries, including 118,849 deliveries (15%) among immigrant women (eAppendix, http://links.lww.com/EDE/A515). The overall risk of gestational diabetes mellitus varied by a woman's region of birth (Table). The risk was more than double among women from the Caribbean and East Asia/Pacific regions, and almost quadrupled among those from South Asia (Table). Among women without a prior live birth, these effect sizes were either unchanged or higher (data not shown).

Although our dataset represents nearly all women who immigrated to Ontario, the period of immigration was only up to year 2000, and those arriving thereafter are not included in this study. Although we could not determine the ethnicity of Canadian-born women, we could infer the ethnicity of immigrants using world region of birth as a proxy. Comparing immigrant groups better deals with the potentially difficult-to-measure interaction among the healthy immigrant effect, ethnicity, and risk of gestational diabetes mellitus. Although we adjusted for some relevant covariates, information on maternal weight, dietary history, and a prior history of gestational diabetes mellitus was not available.

It is noteworthy that women from South Asia, East Asia, and the Pacific (who together represented 44% of all deliveries among immigrants), all have high, but different, risk of gestational diabetes mellitus. This underscores the inadequacy of the general term, “Asian”; more specific descriptors should be used. In addition, the healthy immigrant effect does not appear to be protective against gestational diabetes mellitus, compared with native-born women.

Maternal region of origin may help identify those immigrant women at highest risk in early pregnancy for developing gestational diabetes mellitus.4 Initiation of dietary and activity modification in early pregnancy is now being studied among high-risk women to prevent the onset of this condition.5 Finally, our data might aid in optimizing postpartum screening for type 2 diabetes, because gestational diabetes mellitus is a recognized long-term risk factor for type 2 diabetes, but most women do not develop the condition for many years or at all.6

Marcelo Urquia

Centre for Research on Inner City Health

St. Michael's Hospital

Institute for Clinical Evaluative Sciences

Toronto, ON

Richard H. Glazier

Institute for Clinical Evaluative Sciences

Centre for Research on Inner City Health

Department of Family and Community Medicine

St. Michael's Hospital,

University of Toronto

Toronto, ON, Canada

Howard Berger

Department of Obstetrics and Gynecology

St. Michael's Hospital

University of Toronto

Toronto, ON, Canada

Ivan Ying

Department of Medicine

Schulich School of Medicine and Dentistry

London, ON, Canada

Leanne De Souza

Department of Obstetrics and Gynecology

St. Michael's Hospital

University of Toronto

Toronto, ON, Canada

Joel G. Ray

Departments of Medicine and of Obstetrics and Gynecology

St. Michael's Hospital

Institute for Clinical Evaluative Sciences

University of Toronto

Toronto, ON, Canada

rayj@smh.ca

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REFERENCES

1. Cripe SM, O'Brien W, Gelaye B, Williams MA. Maternal morbidity and perinatal outcomes among foreign-born Cambodian, Laotian, and Vietnamese Americans in Washington state, 1993-2006. J Immigr Minor Health. 2011;13:417–425.
2. Solomon CG, Willett WC, Carey VJ, et al. A prospective study of pregravid determinants of gestational diabetes mellitus. JAMA. 1997;278:1078–1083.Bonde JP, Ramlan-Hansen CH, Olsen J. Trends in sperm counts-the saga continues. Epidemiology. 2011;22:617–619.
3. Urquia ML, Frank JW, Moineddin R, Glazier RH. Immigrants' duration of residence and adverse birth outcomes: a population-based study. BJOG. 2010;117:591–601.
4. Ray JG, Berger H, Lipscombe LL, Sermer M. Gestational prediabetes: a new term for early prevention? Indian J Med Res. 2010;132:251–255.
5. Oostdam N, van Poppel MN, Eekhoff EM, Wouters MG, van Mechelen W. Design of FitFor2 study: the effects of an exercise program on insulin sensitivity and plasma glucose levels in pregnant women at high risk for gestational diabetes. BMC Pregnancy Childbirth. 2009;9:1.
6. Feig DS, Zinman B, Wang X, Hux JE. Risk of development of diabetes mellitus after diagnosis of gestational diabetes. CMAJ. 2008;179:229–234.

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