[1] Univ Hong Kong, Dept Obstet & Gynecol, Hong Kong, Hong Kong, Peoples R China
[2] Natl Taiwan Univ Hosp, Dept Obstet & Gynecol, Taipei, Taiwan
[3] Univ Ulsan, Dept Obstet & Gynecol, Coll Med, Asan Med Ctr, Seoul, South Korea
[4] Jikei Univ, Dept Obstet & Gynecol, Tokyo, Japan
[5] Mahidol Univ, Ramathibodi Hosp, Fac Med, Dept Obstet & Gynecol, Bangkok 10400, Thailand
[6] Changi Gen Hosp, Dept Lab Med, Singapore, Singapore
[7] Hosp Sultanah Aminah, Dept Pathol, Johor Baharu, Johor, Malaysia
[8] Abbott Diagnost, Abbott Pk, IL USA