HANOI, Vietnam — The number of international adoptions has plummeted to its lowest point in 15 years.

The steep decline is attributed largely to crackdowns against baby-selling, a sputtering world economy and efforts by countries to place more children with domestic families.

Adoptions expert Peter Selman at Britain’s Newcastle University has compiled statistics showing that the number of orphans being adopted globally by foreign parents has dropped from a high of 45,000 in 2004 to an estimated 25,000 last year.

Some adoption advocates argue that the decrease also is linked to strict international guidelines known as the Hague Adoption Convention, aimed at protecting children after a rash of baby-selling scandals. These advocates say the U.S. uses the guidelines as a pretext to freeze adoptions altogether from some countries.