[1] Brown Univ, Providence, RI USA
[2] Women & Infants Hosp Rhode Isl, 101 Dudley St, Providence, RI 02905 USA
[3] Univ Iowa Hosp & Clin, 200 Hawkins Dr, Iowa City, IA 52242 USA
[4] Univ Arizona, Tucson, AZ USA
[5] Univ Washington, Sch Med, Dept Family Med, Hlth Sci Ctr, E-304 Box 356391, Seattle, WA 98195 USA
[6] Oregon Hlth & Sci Univ, Dept Obstet & Gynecol, 3181 SW Sam Jackson Pk Rd,Mailstop L466, Portland, OR 97239 USA