[1] Ctr Dis Control & Prevent, Natl Ctr Birth Defects & Dev Disabil, 1600 Clifton Rd,Mail Stop E-86, Atlanta, GA 30329 USA
[2] Ctr Dis Control & Prevent, Epidem Intelligence Serv, Atlanta, GA 30329 USA
[3] Ctr Dis Control & Prevent, Natl Ctr Hlth Stat, Hyattsville, MD USA
[4] Hlth Resources & Serv Adm, Maternal & Child Hlth Bur, Rockville, MD USA