From the Departments of Obstetrics and Gynecology at the 1University of Utah, Salt Lake City, Utah; 2Ohio State University, Columbus, Ohio; 3University of Alabama at Birmingham, Birmingham Alabama; 4University of Texas Southwestern Medical Center, Dallas, Texas; 7University of Chicago, Chicago, Illinois; 8University of Pittsburgh, Pittsburgh Pennsylvania; 9Wake Forest University School of Medicine, Winston-Salem, North Carolina; 10Columbia University, New York, New York; 11Wayne State University, Detroit, Michigan; 12University of Cincinnati, Cincinnati, Ohio; 13Brown University, Providence, Rhode Island; 14Northwestern University, Chicago, Illinois; 15University of Miami, Miami, Florida; 16University of Tennessee, Memphis, Tennessee; 17University of Texas Health Science Center at San Antonio, San Antonio, Texas; 18University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; 19University of Texas Health Science Center at Houston, Houston, Texas; 20Case Western Reserve University, Cleveland, Ohio; and 6The George Washington University Biostatistics Center, Washington, DC, and the 5National Institute of Child Health and Human Development, Bethesda, Maryland.
* For members of the National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network, see the Appendix.
Supported by grants from the National Institute of Child Health and Human Development (HD21410, HD21414, HD27860, HD27861, HD27869, HD27905, HD27915, HD27917, HD34116, HD34122, HD34136, HD34208, HD34210, HD40500, HD40485, HD40544, HD40545, HD40560, HD40512, and HD36801).
Address correspondence to: Robert M. Silver, MD, Department of Obstetrics and Gynecology University of Utah School of Medicine, 30 North 1900 East, Room 308, Salt Lake City, UT 84132; e-mail: [email protected].
