[1] Brown Univ, Women & Infants Hosp, Alpert Sch Med, Div Perinatal Pathol, Providence, RI 02905 USA
[2] RTI Int, Dept Stat & Epidemiol, Res Triangle Pk, NC USA
[3] UTMB Galveston, Dept Pediat Pathol, Galveston, TX USA
[4] UTHSC, San Antonio Sch Med, San Antonio, TX USA
[5] Egleston Hosp, Pathol Lab, Atlanta, GA USA
[6] RTI Int, Dept Stat & Data Anal, Kansas City, MO USA
[7] Tufts Univ, Sch Med, Dept Maternal & Fetal Med, Boston, MA 02111 USA
[8] Primary Childrens Med Ctr, Dept Pediat Pathol, Salt Lake City, UT 84103 USA
[9] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA