A study released today in the Canadian Medical Association Journal confirms previous research showing that the male-to-female ratio for third-born children to women born in India and living in Ontario is higher than the natural rate.

"The findings are highly unlikely to be due to chance," says Dr. Joel Ray, the lead researcher, who is a clinician scientist at St. Michael's Hospital in Toronto.

Dr. Joel Ray of St. Michael's Hospital in Toronto says it would be 'unfair to speculate' why boys are over-represented among third children from Indian immigrant families, but that it is 'unlikely to be due to chance.' (Courtesy of St. Michael's Hospital)

Ray says his research was inspired by the controversial editorial written by Dr. Rajendra Kale, the former interim editor in chief of the CMAJ.

The January 2012 editorial suggested that what Kale called the "repugnant practice" of female feticide, or sex-selective abortion, played a part in previously studied high male-to-female sex ratios in specific ethnic groups in Canada.

The new study, prepared by Ray, Dr. David Henry and Marcelo Urquia, found that the third-child births of Indian-born women were at a ratio of 136 boys to 100 girls.

Contact information If you have more information on the practice of sex-selection in Canada please e-mail investigations@cbc.ca

In comparison, third children of Canadian-born mothers in Ontario were born at the ratio of 105 boys to 100 girls, which is considered about normal for the worldwide average.

Although Ray says he hasn’t found other explanations than selective abortion for why there would be higher male-to-female ratios in the Indian population he says, "it would be unfair to speculate."

Sex selection for a fetus may occur as a result of abortion following an ultrasound, but another possibility is the implantation of embryos selected after in vitro fertilization. An ad in a South Asian newspaper published in Surrey, B.C., offers to help people create the family they want through testing and selecting embryos according to sex.

The practice is against the law in Canada, except in cases of testing for gender-specific diseases, but the clinic that offers the service is across the border in Washington state, where it is legal.

The Indo-Canadian Voice newspaper told CBC News it was unaware the procedure was illegal here and it may reconsider running the ads.

Long-standing issue in India

Balpreet Singh, legal counsel and acting executive director for the World Sikh Association of Canada, says the numbers are not surprising.

"The Indian culture no doubt has a preference for male children, it has been a long-standing issue in India, so it's not a surprise to me that trend is showing up here among immigrant women."

Disappearing daughters All week, check for audio, video and more information about the special series. On Wednesday, CBC Metro Morning's Mary Wiens tells the story of a mother and daughter who host a Punjabi-English radio call-in show on sensitive topics, including female feticide amongst South Asians.

Ray and his co-authors say their research provides a more complete picture than previous research done on sex ratios, because instead of sampling census data, it looks at all 766,688 singleton live births in Ontario between 2002 and 2007.

Each newborn was categorized according to the mother’s country or region of birth: Canada, Europe, South Korea, China, Philippines, rest of East Asia, Pakistan, India, rest of South Asia, and other countries.

The analysis also showed South Korean women in Ontario delivered 786 boys to 653 girls as second children.

However, Ray states that the South Korean sample may be too small to tell if the findings are significant.

Ray says these findings should spark further research into why there are more boys than girls born in some ethnic communities in Canada.

He notes that Ontario is the most ethnically diverse part of the country with the largest ethnic immigrant population.

If you have more information on the practice of sex-selection in Canada please e-mail investigations@cbc.ca

The graphs below were formulated by the CBC from the research report Sex Ratios Among Canadian Liveborn Infants of Mothers from Different Countries. Each blue bar shows the ratio of male births to female births for the corresponding country according to the placement within the family birth order. The study was based on 766,688 live single births in Ontario between 2002 and 2007.