[1] Baylor Coll Med, Dept Obstet & Gynecol, Houston, TX USA
[2] Baylor Coll Med, Div Maternal Fetal Med, Dept Obstet & Gynecol, Houston, TX USA
[3] Univ Texas Austin, Austin Dell Med Sch, Dept Obstet & Gynecol, Austin, TX USA
[4] Univ Toronto, Hosp Sick Children, Dept Pediat, Toronto, ON, Canada
[5] Univ Toronto, St Michaels Hosp, Dept Pediat, Toronto, ON, Canada
[6] Univ Toronto, St Michaels Hosp, Dept Obstet & Gynecol, Toronto, ON, Canada
[7] Johns Hopkins Sch Med, Dept Obstet & Gynecol, Baltimore, MD USA
[8] Univ Colorado, Dept Pediat, Sch Med, Denver, CO USA
[9] George Washington Univ, Natl Childrens Hosp, Dept Pediat, Sch Med & Hlth Sci, Washington, DE USA
[10] Univ Washington, Dept Maternal Fetal Med, Sch Med, Seattle, WA USA
[11] Univ Montreal, Dept Obstet & Gynecol, Ctr Hosp Univ St Justine, Montreal, PQ, Canada
[12] Univ Montreal, Dept Pediat, Montreal, PQ, Canada
[13] Univ N Carolina, Dept Obstet & Gynecol, Sch Med, Chapel Hill, NC USA
[14] Univ Calif San Francisco, Dept Obstet & Gynecol, San Francisco, CA USA
[15] Univ South Carolina, Dept Pediat, Sch Med, Columbia, SC USA