[1] Univ Penn, Dept Obstet Gynecol, Ctr Clin Epidemiol & Biostat, Ctr Res Reprod & Womens Hlth, Philadelphia, PA 19104 USA
[2] Univ Penn, Dept Psychiat, Ctr Clin Epidemiol & Biostat, Ctr Res Reprod & Womens Hlth, Philadelphia, PA 19104 USA
[3] Univ Penn, Dept Med, Philadelphia, PA 19104 USA
[4] Temple Univ, Coll Hlth Profess, Philadelphia, PA 19122 USA
[5] Drexel Univ, Dept Math, Philadelphia, PA 19104 USA