Sofie Bliddal1, Malene Boas2, Linda Hilsted2, Lennart Friis-Hansen2, Ann Tabor2, Ulla Feldt-Rasmussen2. 1. Departments of Medical EndocrinologySection 2132Growth and ReproductionClinical BiochemistryCopenhagen University Hospital (Rigshopitalet), Blegdamsvej 9, 2100 Copenhagen, DenmarkDepartment of Clinical BiochemistrySlagelse-Naestved Hospital, Naestved, DenmarkDepartment of ObstetricsCenter of Fetal Medicine, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark sofiebliddal@gmail.com. 2. Departments of Medical EndocrinologySection 2132Growth and ReproductionClinical BiochemistryCopenhagen University Hospital (Rigshopitalet), Blegdamsvej 9, 2100 Copenhagen, DenmarkDepartment of Clinical BiochemistrySlagelse-Naestved Hospital, Naestved, DenmarkDepartment of ObstetricsCenter of Fetal Medicine, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Abstract
OBJECTIVE: Aberrations in maternal thyroid function and autoimmunity during pregnancy have been associated with negative obstetric outcome. In Denmark, a national iodine fortification program was implemented in the year 2000 with the aim to alleviate the mild-moderate iodine deficiency. Following the iodine implementation, there has been an increase in thyroid autoimmunity in the background population. This study investigates the thyroid status of pregnant Danish women following the iodine fortification program, and a possible association with preterm delivery. DESIGN: Historical cohort study of 1278 randomly selected pregnant Danish women attending the national Down's syndrome screening program. METHODS: The main outcome measures were thyroid status according to laboratory- and gestational-age-specific reference intervals, and association with risk of abnormal obstetric outcome. Antibody-positivity was defined as an antibody-level (thyroid peroxidase and/or thyroglobulin antibodies) above 60 U/ml. RESULTS: Establishing laboratory-specific gestational-age-dependent reference intervals, we found a prevalence of maternal thyroid dysfunction of 10%-15.8% by use of the cut-off suggested by the American Thyroid Association. Thyroid dysfunction was significantly associated with antibody-positivity (P<0.05). No associations were found between preterm delivery and thyroid dysfunction (adjusted OR 0.6, 95% CI: 0.1-2.3) or autoimmunity (adjusted OR 1.1, 95% CI: 0.4-2.7). CONCLUSIONS: After the implementation of the Danish iodine fortification program, the prevalence of thyroid dysfunction and autoimmunity in Danish pregnant women is high - even higher by use of pre-established reference intervals from international consensus guidelines. However, no associations were found with abnormal obstetric outcome. Large randomized controlled trials are needed to clarify the benefit of treating slight aberrations in pregnant women's thyroid function.
OBJECTIVE: Aberrations in maternal thyroid function and autoimmunity during pregnancy have been associated with negative obstetric outcome. In Denmark, a national iodine fortification program was implemented in the year 2000 with the aim to alleviate the mild-moderate iodine deficiency. Following the iodine implementation, there has been an increase in thyroid autoimmunity in the background population. This study investigates the thyroid status of pregnant Danish women following the iodine fortification program, and a possible association with preterm delivery. DESIGN: Historical cohort study of 1278 randomly selected pregnant Danish women attending the national Down's syndrome screening program. METHODS: The main outcome measures were thyroid status according to laboratory- and gestational-age-specific reference intervals, and association with risk of abnormal obstetric outcome. Antibody-positivity was defined as an antibody-level (thyroid peroxidase and/or thyroglobulin antibodies) above 60 U/ml. RESULTS: Establishing laboratory-specific gestational-age-dependent reference intervals, we found a prevalence of maternal thyroid dysfunction of 10%-15.8% by use of the cut-off suggested by the American Thyroid Association. Thyroid dysfunction was significantly associated with antibody-positivity (P<0.05). No associations were found between preterm delivery and thyroid dysfunction (adjusted OR 0.6, 95% CI: 0.1-2.3) or autoimmunity (adjusted OR 1.1, 95% CI: 0.4-2.7). CONCLUSIONS: After the implementation of the Danish iodine fortification program, the prevalence of thyroid dysfunction and autoimmunity in Danish pregnant women is high - even higher by use of pre-established reference intervals from international consensus guidelines. However, no associations were found with abnormal obstetric outcome. Large randomized controlled trials are needed to clarify the benefit of treating slight aberrations in pregnant women's thyroid function.
Authors: Arash Derakhshan; Robin P Peeters; Peter N Taylor; Sofie Bliddal; David M Carty; Margreet Meems; Bijay Vaidya; Liangmiao Chen; Bridget A Knight; Farkhanda Ghafoor; Polina V Popova; Lorena Mosso; Emily Oken; Eila Suvanto; Aya Hisada; Jun Yoshinaga; Suzanne J Brown; Judit Bassols; Juha Auvinen; Wichor M Bramer; Abel López-Bermejo; Colin M Dayan; Robert French; Laura Boucai; Marina Vafeiadi; Elena N Grineva; Victor J M Pop; Tanja G Vrijkotte; Leda Chatzi; Jordi Sunyer; Ana Jiménez-Zabala; Isolina Riaño; Marisa Rebagliato; Xuemian Lu; Amna Pirzada; Tuija Männistö; Christian Delles; Ulla Feldt-Rasmussen; Erik K Alexander; Scott M Nelson; Layal Chaker; Elizabeth N Pearce; Mònica Guxens; Eric A P Steegers; John P Walsh; Tim I M Korevaar Journal: Lancet Diabetes Endocrinol Date: 2020-06 Impact factor: 44.867