[1] Stanford Univ, Sch Med, March Dimes Prematur Res Ctr, Stanford, CA 94305 USA
[2] Stanford Univ, Dept Pediat, Sch Med, Stanford, CA 94305 USA
[3] Stanford Univ, Sch Med, Dept Obstet & Gynecol, Stanford, CA 94305 USA
[4] Univ Tampere, Tampere, Finland
[5] Stanford Univ, Dept Med, Sch Med, Stanford, CA 94305 USA
[6] Stanford Univ, Sch Engn, Dept Bioengn, Stanford, CA 94305 USA
[7] Univ Calif San Francisco, Sch Med, Dept Pediat, Oakland, CA USA
[8] Stanford Univ, Sch Med, Dept Anesthesiol, Stanford, CA 94305 USA
[9] Univ Cincinnati, Sch Med, Dept Pediat, Cincinnati, OH USA
[10] Washington Univ, Sch Med, Dept Obstet & Gynecol, St Louis, MO 63110 USA
[11] Univ Penn, Dept Obstet & Gynecol, Perelman Sch Med, Philadelphia, PA 19104 USA
[12] Univ Chicago, Pritzker Sch Med, Dept Human Genet, Chicago, IL 60637 USA
[13] March Dimes Fdn, White Plains, NY USA