[1] Vanderbilt Univ, Med Ctr, Inst Med & Publ Hlth, Vanderbilt Epidemiol Ctr, Nashville, TN 37235 USA
[2] Vanderbilt Univ, Sch Med, Dept Obstet & Gynecol, Nashville, TN 37212 USA
[3] Brown Univ, Dept Epidemiol, Brown Sch Publ Hlth, Providence, RI 02912 USA
[4] Brown Univ, Dept Obstet & Gynecol, Brown Med Sch, Providence, RI 02912 USA
[5] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Epidemiol, Chapel Hill, NC USA
[6] Vanderbilt Univ, Dept Biostat, Med Ctr, Inst Med & Publ Hlth, Nashville, TN USA
[7] NIEHS, Epidemiol Branch, NIH, Res Triangle Pk, NC 27709 USA