[1] Univ Texas Med Branch, Galveston, TX 77555 USA
[2] Boston Med Ctr, Boston, MA USA
[3] Univ Calif San Diego, La Jolla, CA 92093 USA
[4] Denver Hosp Author, Denver, CO USA
[5] Maricopa Cty Gen Hosp, Phoenix, AZ USA
[6] Univ Massachusetts Baystate, Div Maternal Fetal Med, Dept Obstet & Gynecol, Springfield, MA USA
[7] Thomas Jefferson Univ Hosp, Philadelphia, PA 19107 USA
[8] Indiana Univ, Dept Obstet & Gynecol, Carmel, IN USA
[9] Ochsner Med Ctr, New Orleans, LA USA
[10] Northwestern Univ, Feinberg Sch Med, Chicago, IL 60611 USA
[11] Med Univ South Carolina, Charleston, SC 29425 USA
[12] Univ Calif Irvine, Irvine, CA USA
[13] Duke Univ, Med Ctr, Durham, NC USA
[14] Oregon Hlth & Sci Univ, Portland, OR 97201 USA
[15] Univ N Carolina, Chapel Hill, NC USA
[16] Univ Colorado Denver, Aurora, CO USA
[17] Reg Obstet Consultants, Chattanooga, TN USA
[18] Prisma Hlth, Greenville, SC USA
[19] Sera Prognost, Salt Lake City, UT USA
[20] Sera Prognost, Draper, UT USA