Makes me wonder if there was a lot of thought given to ethics when planning this study. If we've learned anything, we should know that people will be terrible enough to want to "cure" homosexuality or detect it before birth, like trisomy 21, if it ever will become possible - and research like this will lead to that.
Tangentially related; question to those who are pro-choice: why is regular abortion okay but sex-selective abortion, aborting downsies, etc. not? My understanding of the pro-choice argument is that if a fetus is not yet a person, it's not wrong to kill it. Why is it more wrong to abort a fetus because it is a boy/girl? I am pro-life and so view this differently, hence not understanding the reasoning here.
In that lens, imagine a scenario where a woman is happy to be pregnant and excited about becoming a parent. Then she learns the child will be male, and she decides to abort it. There's a wide gulf between between the harm of "didn't want to be a parent" and the disappointment of "didn't want a son". It may help to imagine this with even more trivial features: "oh the baby is going to have blue eyes? never mind then...".
For something like trisomy-21, I find myself of mixed mind. On one hand, there are many things that can happen to a child through their life that could end up posing a similar impediment to the child and burden on their parent. On the other hand, since we're able to detect it so early, perhaps it is the best way to minimize harm.