[1] KK Womens & Childrens Hosp, Dept Paediat, Singapore, Singapore
[2] KK Womens & Childrens Hosp, KK Res Ctr, Singapore, Singapore
[3] Duke NUS Med Sch, Ctr Quantitat Med, Singapore, Singapore
[4] Univ Tampere, Dept Int Hlth, FIN-33101 Tampere, Finland
[5] Duke NUS Med Sch, Singapore, Singapore
[6] KK Womens & Childrens Hosp, Dept Reprod Med, Singapore, Singapore
[7] Natl Univ Singapore, Natl Univ Hlth Syst, Yong Loo Lin Sch Med, Dept Obstet & Gynaecol, Singapore 117548, Singapore
[8] Univ Southampton, MRC Life Course Epidemiol Unit, Southampton, Hants, England
[9] Univ Southampton, NIHR Southampton Biomed Res Ctr, Southampton, Hants, England
[10] Univ Hosp Southampton NHS Fdn Trust, Southampton, Hants, England
[11] Univ Auckland, Liggins Inst, Auckland 1, New Zealand
[12] ASTAR, Singapore Inst Clin Sci, Singapore, Singapore
[13] KK Womens & Childrens Hosp, Dept Maternal Fetal Med, Singapore, Singapore
[14] Natl Univ Singapore, Saw Swee Hock Sch Publ Hlth, Singapore 117548, Singapore
[15] Natl Univ Singapore, Natl Univ Hlth Syst, Yong Loo Lin Sch Med, Dept Paediat, Singapore 117548, Singapore