[1] Drexel Univ, Coll Med, Div Pulm Crit Care & Sleep Med, Philadelphia, PA 19104 USA
[2] Drexel Dornsife Sch Publ Hlth, Dept Epidemiol & Biostat, Philadelphia, PA USA
[3] Drexel Univ, Coll Med, Philadelphia, PA 19104 USA
[4] Drexel Univ, Coll Med, Dept Obstet & Gynecol, Div Maternal Fetal Med, Philadelphia, PA 19104 USA