Use of carbimazole, thiamazole and propylthiouracil during pregnancy in Germany


The treatment of Graves' disease in girls and women of childbearing age is particularly challenging due to the potential occurrence of pregnancy. Failure to treat the hyperthyroidism associated with the disease during pregnancy is associated with risks for the pregnancy, the health of the child (spontaneous abortions, premature birth, stillbirth, low birth weight), and the health of the mother (thyrotoxic crisis). There is also an increased risk of congenital malformations associated with drug treatment of the disease with thiamazole (TMZ) and its prodrug carbimazole (CMZ) during pregnancy. The third drug available for treatment, propylthiouracil (PTU), has not been clearly shown to cause malformations, but PTU should not be used routinely because of the increased risk of acute liver failure.

The Federal Institute for Drugs and Medical Devices (BfArM) has issued the following recommendations for thyrostatic therapy of girls and women of childbearing age:
  • Women of childbearing age must use effective methods of contraception during treatment with carbimazole or thiamazole.
  • Hyperthyroidism in pregnant women should be adequately treated to prevent the occurrence of serious maternal and fetal complications.
  • Carbimazole or thiamazole should be used during pregnancy only after performing a rigorous individualized benefit-risk assessment and only at the lowest effective dose without additional administration of thyroid hormones.

In 2018, the European Thyroid Association's guideline on the management of Graves' disease also recommended considering a switch from PTU to TMZ or CMZ after completion of the sensitive phase of organogenesis under individual risk-benefit assessment in order to reduce the risk of maternal liver failure.

In this context, the German Federal Institute for Drugs and Medical Devices (BfArM) wanted to assess the use of ATD in girls and women of childbearing age in Germany and to examine whether the recommendations regarding ATD use in pregnancy are followed. Therefore, the aim of our study was to calculate the prescription prevalence of ATD in women of childbearing age, to assess the occurrence of pregnancies under ATD and to examine switching patterns between CMZ/MMI and PTU before and during pregnancy and their changes over time.

Funding period

Begin:   December 2020
End:   April 2022


  • Federal Institute for Drugs and Medical Devices


Dr. rer. medic. Tania Schink

Selected project-related publications

    Articles without peer-review

  • Schink T, Kollhorst B, Haug U. Verordnung von Thyreostatika bei Frauen im gebärfähigen Alter und in der Schwangerschaft. Bulletin zur Arzneimittelsicherheit - Informationen aus BfArM und PEI. 2023;2:39-43.
  • Presentations at scientific meetings/conferences

  • Schink T, Kollhorst B, Haug U. Antithyroid drug use before and during pregnancy: Assessment of switching patterns and changes over time. 39th International Conference on Pharmacoepidemiology & Therapeutic Risk Management (ICPE), 23-27 August 2023, Halifax, Canada. (Abstract published in: Pharmacoepidemiology and Drug Safety. 2023;32(S1):8-9)