Refused to participate n = 291 Invited n = 1114 Refused to participate n = 291 Gestational week 14 ±2 Included n = 823 (74%) Excluded n = 29 (n=12 from South and Central America and n=17 from African countries due to small sample) Women from Europe, Asia and Middle East/ North Africa n = 794 (96%) Excluded n = 75 (12 abortion, 6 stillbirth, 1 neonatal death, 7 moved out of district, 10 twins) Birth Study sample, with preterm neonates n = 758 (92%) Excluded n = 39 (39 preterm birth) Birth ≥ 37 weeks Main study sample, with birth weight n = 719 (87%)