[1] Univ New Mexico, Dept Pediat, Hlth Sci Ctr, Albuquerque, NM 87131 USA
[2] Univ Utah, Sch Med, Dept Pediat, Div Neonatol, Salt Lake City, UT USA
[3] Case Western Reserve Univ, Rainbow Babies & Childrens Hosp, Dept Pediat, Cleveland, OH 44106 USA
[4] RTI Int, Stat & Epidemiol Unit, Rockville, MD USA
[5] RTI Int, Stat & Epidemiol Unit, Res Triangle Pk, NC USA
[6] Emory Univ, Sch Med, Dept Pediat, Atlanta, GA USA
[7] Childrens Healthcare Atlanta, Atlanta, GA USA
[8] Indiana Univ Sch Med, Dept Pediat, Indianapolis, IN 46202 USA
[9] Brown Univ, Women & Infants Hosp, Dept Pediat, Providence, RI 02908 USA
[10] Univ Texas Houston, Sch Med, Dept Pediat, Houston, TX USA
[11] Cincinnati Childrens Hosp Med Ctr, Dept Pediat, Cincinnati, OH 45229 USA
[12] Univ Cincinnati, Coll Med, Cincinnati, OH USA
[13] Univ Iowa, Dept Pediat, Iowa City, IA 52242 USA
[14] Stanford Univ, Sch Med, Dept Pediat, Div Neonatal & Dev Med, Palo Alto, CA 94304 USA
[15] Lucile Packard Childrens Hosp, Palo Alto, CA USA
[16] Tufts Med Ctr, Floating Hosp Children, Dept Pediat, Div Newborn Med, Boston, MA USA
[17] Duke Univ, Dept Pediat, Durham, NC 27706 USA
[18] Wayne State Univ, Dept Pediat, Detroit, MI 48202 USA
[19] Univ Alabama Birmingham, Div Neonatol, Birmingham, AL USA
[20] Yale Univ, Sch Med, Dept Pediat, New Haven, CT 06510 USA
[21] Univ Texas SW Med Ctr Dallas, Dept Pediat, Dallas, TX 75390 USA
[22] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA