The author mentions some of the serious ethical concerns:
Any discussion of sex selection is haunted by the spectre of the millions of missing girls of India and China. The 2000 Chinese census showed there were 117 boys under the age of five to every 100 girls. A similar trend is reported in India, which also has a deep-seated cultural preference for boys. ...But the story fails to discuss what seems to me to be the gravest moral problem with this practice: It entails the killing of innocent human beings. Let me explain.
In a Mori poll, 82% of the [British] population opposed sex selection for non–medical reasons. As the report said, "A great many respondents felt that sex selection was unqualifiedly wrong because it involved interference with divine will or with what they saw as the intrinsically virtuous course of nature." There was also mention of sex selection being a little farther down a slippery slope towards designer babies.
And then the real clincher: wasn't sex selection for the benefit of the parents, rather than of the child? The report noted that, among some respondents, "The view was that it is one thing to wish to have a child of one sex rather than the other and another thing to take steps to bring it about, since positive intervention in this area changes one's relationship to the outcome, replacing hopes with expectations… Respect for the future child's value as an individual precludes the exercise of control by parents over the kind of child it is to be, including over its sex."
The couples in the story each used IVF to create a number of human embryos, which were then screened for their gender via PGD (PGD is also used to screen for diseases and other traits). Only embryos with the desired gender were transferred into the mother, potentially leading to implantation in the uterus and then (nine months later) birth. Presumably the other, undesirable embryos were discarded (killed).
The whole point of using PGD for sex selection is to "weed out" those embryonic humans with the "wrong" sex, "selecting" those with the right one. And since human embryos are distinct, living and whole organisms of the species Homo sapiens (just at a very early stage of their development), to kill an embryo is to kill a young human being.
We've talked on this blog about sex-selection abortion -- abortion because of the baby's gender -- but sex selection before implantation in the mother's womb is really no morally different: Offspring with the desired gender are allowed to live, and the others are killed.