Participants and follow-up.
Details of the inclusion and exclusion criteria and randomization are available in the original trial publication.All participants were seen at the health center at 4-week intervals until 36 completed gestation weeks and weekly thereafter. At each visit, the mothers underwent an interview, a routine antenatal investigation, and blood sampling. From the blood samples taken at the clinic, 100 μL (two spots, each 50 μL) was applied to Whatman FTA filter paper (Whatman plc, Maidstone, UK), air-dried, and placed in individually sealed plastic bags with a desiccant. The sample bags were stored in dry conditions at room temperature prior to transport to the Tampere University, Finland. The gathered dried blood spot (DBS) samples were analyzed by first extracting the DNAPelvic ultrasound to assess fetal biparietal diameter and femur length was performed for all study participants at the first antenatal visit and for a random subgroup of 341 women at each subsequent visit. Pelvic ultrasound was done with a portable analyzer by a research nurse (Aloka SSD-500; Aloka Co. Ltd., Tokyo, Japan, or Hitachi EUB 310; Hitachi, Ltd., Tokyo, Japan). Hadlock tables were used to calculate fetal age at the first visit.