1. University of Texas Health Science Center at San Antonio; San Antonio; TX
2. RTI International; Research Triangle Park; NC
3. Pregnancy and Perinatology Branch; the Eunice Kennedy Shriver National Institute of Child Health and Human Development; National Institutes of Health; Bethesda; MD
4. University of Utah School of Medicine and Intermountain Health Care; Salt Lake City; UT
5. University of Texas Medical Branch at Galveston; Galveston; TX
6. Brown University School of Medicine; Providence; RI
7. Emory University School of Medicine; Atlanta; GA
8. Rollins School of Public Health; Emory University; Atlanta; GA
9. Columbia University Medical Center; New York; NY