[1] Boston Univ, Sch Publ Hlth, Dept Community Hlth Sci, Boston, MA 02118 USA
[2] Boston Univ, Sch Med, Sect Hematol & Oncol, Boston Med Ctr, Boston, MA 02118 USA
[3] Brown Univ, Dept Epidemiol, Warren Alpert Sch Med, Providence, RI 02912 USA
[4] Brown Univ, Dept Obstet & Gynecol, Warren Alpert Sch Med, Providence, RI 02912 USA
[5] Brown Univ, Publ Hlth Program, Providence, RI 02912 USA