“CREATE the family you want: boy or girl,” ran an advertisement for the Washington Centre for Reproductive Medicine, an American clinic located two hours' drive south of the Canadian border. Using in vitro fertilisation to select the sex of a child is illegal in Canada, and the ad was soon withdrawn. But for a while it ran in the Indo-Canadian Voice, a newspaper for South Asian migrants.

Sex selection is overwhelmingly associated with China and India. But it may be spreading to rich countries, too. A study published in the Canadian Medical Association Journal (CMAJ) on April 16th looked at 767,000 births in Ontario province from 2002-07 and checked them against the mother's country of origin.

For first-born children, the sex ratio was normal—105 baby boys to 100 baby girls (since boys are slightly more vulnerable to childhood diseases, this ratio provides for equal numbers at marriageable age). For second children, the ratio was normal for mothers born in Canada. But mothers born in South Korea bore 120 boys for each 100 girls. And for Indian, Filipina and other East Asian mothers, the ratio was 110-111 to 100. The explanation for this pattern in India is that couples welcome a first-born of either sex, but if she is a daughter, then some ensure the second child is a son. That applies even more to third children: in Ontario, mothers born in India gave birth to 1,883 sons and 1,385 daughters, a hugely distorted ratio of 136 to 100.

The study proved controversial. Jonathan Kay, a columnist for the National Post, argued that it should jolt Canada into drafting a new abortion law (the country has had no legal limits on abortion since 1988). An earlier editorial in the CMAJ argued that doctors should not tell parents the sex of their child until the 30th week of pregnancy. The Society of Obstetricians and Gynaecologists rejected that proposal.

Prabhat Jha, of the University of Toronto, pointed out that skewed sex ratios might be caused by things other than selective abortion, such as higher migration rates of women who are expecting a son. The study's main author, Joel Ray, conceded that it does not show why ratios are distorted. Fair enough, but data from the 2001 and 2006 censuses showed even greater discrepancies for third children. In India and China sex-selective abortions are seen as crimes against humanity. Why should Canada view them any differently?