Introduction: Maternal iodine requirements increase during pregnancy. Studies performed before the introduction of mandatory iodine fortification of salt in Denmark in 2000 showed that pregnant women with no intake of iodine-containing supplements were moderately iodine-deficient and showed signs of thyroidal stress. We investigated the intake of iodine-containing supplements and urinary iodine excretion in Danish pregnant women after the introduction of iodine fortification of salt.
Material and methods: We conducted a cross-sectional study between June and August 2012 in an area of Denmark where iodine deficiency had previously been moderate. Pregnant women coming to Aalborg University Hospital for obstetric ultrasound were recruited consecutively. Participants filled in a questionnaire and handed in a spot urine sample for measurement of iodine and creatinine.
Results: Among the pregnant women included (n = 245) 84.1% reported an intake of iodine-containing supplements, and compared with those not taking iodine supplements the median urinary iodine concentration was significantly higher in this group: 109 g/l (25th-75th percentile: 66-191 µg/l). On the other hand, the median urinary iodine concentration was considerably below the recommended level, even for the non-pregnant state in pregnant women with no iodine supplement intake: 68 µg/l (35-93 µg/l), p < 0.001.
Conclusion: The majority of pregnant women took iodine-containing supplements, but the subgroup of non-users was still iodine-deficient after the introduction of iodine fortification of salt. Iodine supplement intake during pregnancy in Denmark should be officially recommended.
Funding: The study was supported by a grant from Musikforlæggerne Agnes og Knut Mørks Fond and from Speciallæge Heinrich Kopps Legat.
Trial registration: not relevant.