[1] Univ British Columbia, Dept Obstet & Gynaecol, Vancouver, BC, Canada
[2] Univ British Columbia, Dept Obstet & Gynaecol, Div Reprod Endocrinol & Infertil, Vancouver, BC, Canada
[3] Univ British Columbia, Sch Populat & Publ Hlth, Vancouver, BC, Canada
[4] Childrens & Womens Hosp, Vancouver, BC, Canada
[5] Hlth Ctr British Columbia, Vancouver, BC, Canada
[6] McMaster Univ, Dept Obstet & Gynecol, Hamilton, ON, Canada
[7] McMaster Univ, Dept Hlth Res Methods Evidence & Impact, Hamilton, ON, Canada
[8] Univ Laval, Dept Pediat, Fac Med, Quebec City, PQ, Canada
[9] Univ Laval, Res Ctr, CHU Quebec, Quebec City, PQ, Canada
[10] Karolinska Inst, Dept Med Solna, Stockholm, Sweden
[11] NYU Grossman Sch Med, Div Maternal Fetal Med, Dept Obstet & Gynecol, New York, NY USA
[12] Rutgers Robert Wood Johnson Med Sch, Div Epidemiol & Biostat, Dept Obstet Gynecol & Reprod Sci, New Brunswick, NJ USA
[13] Rutgers Robert Wood Johnson Med Sch, Cardiovasc Inst New Jersey, New Brunswick, NJ USA
[14] Rutgers Robert Wood Johnson Med Sch, Dept Med, New Brunswick, NJ USA
[15] Rutgers Sch Publ Hlth, Dept Biostat & Epidemiol, Piscataway, NJ USA
[16] Rutgers Robert Wood Johnson Med Sch, Environm & Occupat Hlth Sci Inst, Piscataway, NJ USA