A study has revealed that nearly 90 percent of newborns in the United States are getting tested for almost 29 of the few thousand genetic disorders that need early treatment to avoid death, retardation or other serious problems.

Though the federal health agency has not issued national screening guidelines, but a March of Dimes report issued Wednesday says that as of June 1, 40 states across America required testing for more than 20 of those disorders.

Now, Washington, D.C. and other 13 states have made it mandatory for testing of every newborn for the entire list of 29 conditions, which range from sickle cell anemia and cystic fibrosis to lesser known diseases such as the metabolic disorder LCHAD.

The measure was also followed by New Hampshire that began testing for all 29 conditions on July 1, after the report's deadline. There has been a steady increase in the number of babies that were screened for genetic disorders.

In 2005, only 38 percent of babies were born in states with intensive screening while the number plunged to 64 percent last year. However, in 2007, almost 87.5 percent of newborns, or about 3.6 million babies are getting tested for the genetic disorders.