[1] Karolinska Inst, Dept Global Publ Hlth, Solna, Stockholm, Sweden
[2] Karolinska Inst, Dept Med, Clin Epidemiol Div, Solna, Stockholm, Sweden
[3] Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden
[4] Karolinska Univ Hosp, Dept Neonatal Med, Stockholm, Sweden
[5] Karolinska Univ Hosp, Dept Womens Hlth, Stockholm, Sweden
[6] Oregon Hlth & Sci Univ, Dept Nurse Midwifery, Sch Nursing, Portland, OR USA
[7] Oregon Hlth & Sci Univ, Dept Obstet & Gynecol, Portland, OR USA