University of Oulu

Turunen S, Vääräsmäki M, Leinonen M, Gissler M, Männistö T, Suvanto E: The Increased Trend of Medical Treatment for Thyroid Diseases during Pregnancy: A 13-Year National Study. Eur Thyroid J 2021;10:230-236. doi: 10.1159/000515125

The increased trend of medical treatment for thyroid diseases during pregnancy : a 13-year national study

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Author: Turunen, Suvi1; Vääräsmäki, Marja1; Leinonen, Maarit2;
Organizations: 1Department of Obstetrics and Gynecology, PEDEGO Research Unit, Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland
2Information Services Department, Finnish Institute of Health and Welfare, Helsinki, Finland
3Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
4Northern Finland Laboratory Centre Nordlab, Oulu, Department of Neurobiology, Care Sciences and Society, Finland Karolinska Institute, Stockholm, Sweden
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.6 MB)
Persistent link:
Language: English
Published: Karger, 2021
Publish Date: 2021-11-02


Objective: Thyroid dysfunction affects up to 5–7% of all pregnancies. The rates of thyroid hormone use in nonpregnant population have substantially increased in recent years. The aim of this study was to assess possible changes in the use of levothyroxine substitution and antithyroid drugs over time in pregnant women.

Methods: The study data consisted of all singleton pregnancies (N = 736,873) between 2004 and 2016 in Finland collected from the Finnish Medical Birth Register. The Prescription Register and Special Refund Entitlement Register provided information on levothyroxine and antithyroid drug purchases. The annual rates of levothyroxine and antithyroid drug prescription redemptions were explored to estimate changes in exposure rates to thyroid medication from 2004 to 2016. Joinpoint regression analyses were performed to explore interannual variability in levothyroxine and antithyroid drug treatment.

Results: There was more than a five-fold increase in levothyroxine use during the study period; in 2004, 1.1% of pregnant women had levothyroxine treatment, and by 2016, the prevalence increased to 6.2%. In addition, we observed a slight increase in antithyroid medication during pregnancy, but antithyroid drug use during pregnancy overall was very rare. In 2004, 0.05% of pregnant women used antithyroid drugs, and by 2016, this percentage had increased to 0.14%.

Conclusions: Our study shows that the rate of levothyroxine use in pregnancy has markedly increased. This suggests that tracing and screening relevant patients and awareness of thyroid disorders on pregnancy and their significance for the pregnancy outcome have increased and the threshold to treat thyroid disorders has declined.

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Series: European thyroid journal
ISSN: 2235-0640
ISSN-E: 2235-0802
ISSN-L: 2235-0640
Volume: 10
Issue: 3
Pages: 230 - 236
DOI: 10.1159/000515125
Type of Publication: A1 Journal article – refereed
Field of Science: 3123 Gynaecology and paediatrics
Funding: This work was supported in part by the Northern Ostrobothnia Hospital District (Dr. Turunen), the Drugs and Pregnancy Project of the National Institute for Health and Welfare (THL), Finnish Medicines Agency (FIMEA), and Social Insurance Institution of Finland (Kela) (Prof. Gissler and Dr. Leinonen).
Copyright information: © 2021 European Thyroid Association. Published by S. Karger AG, Basel. This is the accepted manuscript version of an article published by S. Karger AG in European Thyroid Journal 2021;10:230-236. doi: 10.1159/000515125 and available on