According to the author, why have Americans turned to international adoptions as noted in the nonfiction book, The Lost Daughters of China?

According to the author, the wide availability of birth control and abortion in the United States, as well as increased acceptance of single mothers has led to a dramatic decline in the number of American infants given up for adoption. The costs are even more prohibitive than with international adoption, the waits often longer, and the chances that an adoptive mother will change her mind are higher. The legality of domestic adoptions can also be challenged.