12 Apr Among Indian Immigrants to Canada, Female Fetuses Aborted More Commonly than Male

MedicalResearch.com Interview with: [caption id="attachment_23288" align="alignleft" width="200"] Dr. Marcelo Urquia[/caption] Marcelo L. Urquia PhD PhD, MSc, Mg Public Health, BA Scientist, Li Ka Shing Knowledge Institute St. Michael’s Hospital Assistant Professor, Dalla Lana School of Public Health, University of Toronto  MedicalResearch.com: What is the background for this study? What are the main findings? Dr. Urquia: In most populations the sex ratio at birth, that is, ratio of male newborns to female newborns, is about 103 to 107 males per 100 females. This is well established and does not substantially vary according to whether a woman had one or two previous children of the same sex, as each pregnancy is an independent event. However, it is known that several parts of Asia characterize for having son-biased sex ratios at birth. As countries from Asia, such as India and China are the top contributors of births to immigrant women in Canada, we wanted to verify whether son-biased sex ratios were present in Canada. Since induced abortion following prenatal sex determination using ultrasonography has been hypothesized to be a major mechanism that may explain the distorted sex ratios observed in Asia, we also studied the connection between the probability of having boys after induced abortions. In our first study entitled “Sex ratios after induced abortion” published in CMAJ (http://www.cmaj.ca/lookup/doi/10.1503/cmaj.151074), which used Ontario health care records, we found that sex ratios among Canadian-born women in Ontario were within the expected, irrespective of birth order. The sex ratio among immigrant women from India with two prior girls was 196 males per 100 females for the third live birth. Among Indian immigrant women with two prior daughters the sex ratio increased to 326 males per 100 females if they have had induced abortions preceding the third birth, to 409 males per 100 females if they have had more than one induced abortion since the last newborn child, and to 663 males per 100 females if they have had at least one preceding abortion after 14 weeks of gestation (when the sex of the fetus can be accurately estimated by ultrasonography). These findings suggest that among Indian immigrants to Ontario induced abortions of female fetuses are much more common than induced abortions of male fetuses, which helps explain the deficit in the expected number of female newborns. In our companion paper entitled “Variations in male-female infant ratios among births toCanadian- and Indian-born mothers, 1990-2011: a population-based register study” and published in CMAJ Open (insert URL), we used national birth certificate data and verified that the patterns observed in Ontario are very likely to apply to all Canadian provinces. Moreover, son-biased sex ratios at birth among Indian immigrants have existed in Canada since the early 1990’s. The deficit in the expected number of girls to Indian immigrants over the last two decades in Canada is in between 3211 to 5921.