[1] Univ Puerto Rico, Sch Med, Dept Obstet & Gynecol, San Juan, PR 00936 USA
[2] Univ Puerto Rico, Dept Biostat & Epidemiol, Grad Sch Publ Hlth, Canc Control & Populat Sci Program,Comprehens Can, San Juan, PR 00936 USA
[3] Univ Puerto Rico, Puerto Rico Clin & Translat Res Consortium, San Juan, PR 00936 USA
[4] Ctr Dis Control & Prevent, Atlanta, GA USA