Sofie Bliddal1, Malene Boas2, Linda Hilsted3, Lennart Friis-Hansen4, Anders Juul2,5, Torben Larsen6, Ann Tabor5,7, Jens Faber5,8, Dorthe Hansen Precht9, Ulla Feldt-Rasmussen1,5. 1. Departments of Medical EndocrinologySection 2132. 2. Departments of Growth and Reproduction. 3. Departments of Clinical BiochemistryCopenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark. 4. Department of Clinical BiochemistryHilleroed Hospital, Hilleroed, Denmark. 5. Faculty of Health and Medical SciencesUniversity of Copenhagen, Copenhagen, Denmark. 6. Department of Foetal MedicineCopenhagen University Hospital (Holbaek Hospital), Holbaek, Denmark. 7. Department of ObstetricsCentre of Foetal Medicine, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark. 8. Department of Medicine OEndocrine Unit, Copenhagen University Hospital (Herlev Hospital), Herlev, Denmark. 9. Department of Child PsychiatryCopenhagen University Hospital (Roskilde), Roskilde, Denmark.
Abstract
OBJECTIVE: The presence of thyroid antibodies in pregnancy has been associated with preterm birth. In the non-pregnant population, the implementation of the Danish iodine fortification program has increased the prevalence of thyroid antibodies. This study investigated the prevalence of thyroid peroxidase antibodies (TPOAbs) and thyroglobulin antibodies (TgAbs) in pregnant Danish women before, during and after implementation of the iodine fortification program and association with preterm birth. DESIGN: Comparative cohort study of 1368 pregnancies from three cohorts gathered before (1996-1998), during (2000-2003) and after (2008-2009) the iodine fortification program. METHODS: In cohort 1 (n = 297), TPOAbs were measured (DYNOtest (BRAHMS)). In cohorts 2 (n = 148) and 3 (n = 923), both TPOAbs and TgAbs were measured (Kryptor immunofluorescent assay (BRAHMS)). The prevalence and effect of antibody positivity were explored using three cut-offs: TPOAbs and/or TgAbs >100 kU/L, TPOAbs and/or TgAbs >60 kU/L and TPOAbs >30 and/or TgAbs >20 kU/L. National preterm birth data were extracted from the National Birth Registry. RESULTS: In the three cohorts, TPOAb levels >60 kU/L were found in 5.4, 8.1 and 12.0% (χ2(2, n = 1367) = 11.7, P = 0.003) respectively, and TPOAbs and/or TgAbs >60 kU/L in 8.1 and 16.2% in cohorts 2 and 3 respectively (χ2(2, n = 1070) = 6.5, P = 0.01). TgAb levels (>20 kU/L) had increased plenty-fold from cohort 2 to 3 (χ2(1, n = 1071) = 136.5, P < 0.001). Preterm birth occurred in 4.1% of all pregnancies with no effect from antibody positivity (TPOAbs and/or TgAbs >60 kU/L, χ2(1, n = 1039) = 0.0, P = 0.98, aOR = 1.1, 95% CI (0.4-2.7)). The national preterm birth-rate showed no increase over the same period. CONCLUSIONS: Thyroid antibody positivity in Danish pregnant women has more than doubled upon the implementation of the iodine fortification program without an increase in preterm birth-rate.
OBJECTIVE: The presence of thyroid antibodies in pregnancy has been associated with preterm birth. In the non-pregnant population, the implementation of the Danish iodine fortification program has increased the prevalence of thyroid antibodies. This study investigated the prevalence of thyroid peroxidase antibodies (TPOAbs) and thyroglobulin antibodies (TgAbs) in pregnant Danish women before, during and after implementation of the iodine fortification program and association with preterm birth. DESIGN: Comparative cohort study of 1368 pregnancies from three cohorts gathered before (1996-1998), during (2000-2003) and after (2008-2009) the iodine fortification program. METHODS: In cohort 1 (n = 297), TPOAbs were measured (DYNOtest (BRAHMS)). In cohorts 2 (n = 148) and 3 (n = 923), both TPOAbs and TgAbs were measured (Kryptor immunofluorescent assay (BRAHMS)). The prevalence and effect of antibody positivity were explored using three cut-offs: TPOAbs and/or TgAbs >100 kU/L, TPOAbs and/or TgAbs >60 kU/L and TPOAbs >30 and/or TgAbs >20 kU/L. National preterm birth data were extracted from the National Birth Registry. RESULTS: In the three cohorts, TPOAb levels >60 kU/L were found in 5.4, 8.1 and 12.0% (χ2(2, n = 1367) = 11.7, P = 0.003) respectively, and TPOAbs and/or TgAbs >60 kU/L in 8.1 and 16.2% in cohorts 2 and 3 respectively (χ2(2, n = 1070) = 6.5, P = 0.01). TgAb levels (>20 kU/L) had increased plenty-fold from cohort 2 to 3 (χ2(1, n = 1071) = 136.5, P < 0.001). Preterm birth occurred in 4.1% of all pregnancies with no effect from antibody positivity (TPOAbs and/or TgAbs >60 kU/L, χ2(1, n = 1039) = 0.0, P = 0.98, aOR = 1.1, 95% CI (0.4-2.7)). The national preterm birth-rate showed no increase over the same period. CONCLUSIONS: Thyroid antibody positivity in Danish pregnant women has more than doubled upon the implementation of the iodine fortification program without an increase in preterm birth-rate.
Authors: J Sun; D Teng; C Li; S Peng; J Mao; W Wang; X Xie; C Fan; C Li; T Meng; S Zhang; J Du; Z Gao; Z Shan; W Teng Journal: J Endocrinol Invest Date: 2019-07-01 Impact factor: 4.256