The U.S. teen birth rate in 2009 fell to its lowest point in almost 70 years of record-keeping - a decline that stunned experts who believe it's partly due to the recession. . . . A decline in immigration to the United States, blamed on the weak job market, is another factor cited for the lower birth rate. A large proportion of immigrants are Hispanic, and Hispanics accounted for nearly 1 in 4 births in 2009. The birth rate among Hispanic teens is the highest of any ethnic group with 70 births per 1,000 girls in 2009. However, that rate, too, was down from the previous year.http://gazettenet.com/2010/12/22/us-teen-birth-rate-hits-all-time-low
As is the case with many of our other social problems, the "teen birth rate" is in large part the "illegal immigrant birth rate".