The entire title is: Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of Men.
I only got about a fifth through. Her writing is a bit cold and dull, and has been plumped out for more pages. There's 269 pages of text, long prologue and long epilogue, and Notes and Index at about 50 pages. I think it would have been very good at about 75 pages of text and then just have about 50 pages of references.
Her point is that she's found a lot of demographers who are finding that we will have more boys than girls in the world very soon. Imagine what happens then -- bride selling, brothels, etc. -- because there won't be enough girls for each boy to have one. Almost all countries have people trying to have boys because they're more important. They do that usually by sex-selection via ultrasound. The US has caused this by developing the ultrasound.
The US has the opposite -- we have more girls because we like pink and princess parties, etc.
What she's reporting is contained in the first couple chapters; I skimmed through the others. She's just adding more of the same from different places in the rest of the book.
And, this is a publisher I hadn't seen before, PublicAffairs Books and they have "good books about things that matter." But they didn't watch what she was writing. She said that when a Chinese couple got a boy, the "right egg dropped into the uterus." Apparently she doesn't know that it's the sperm that brings the gender. And then she talked only about people in other countries using sex-selection because they've used fertility drugs. Well, a lot of women in the US do that, too. In fact, instead of just coming down to two, like happened for so many years, some doctors have become willing to bring the batch of fetuses down to one.
I get annoyed when I have to read the same data from so many demographers and parents, so I didn't finish it. Maybe you'd like it better.