Antithyroid drug treatment and pregnancy outcomes among women with hyperthyroidism in pregnancy: A Norwegian population-based registry-linkage study
DOI:
https://doi.org/10.5324/nje.v29i1-2.4048Abstract
Aims: The aim of this study was two-fold: i) to describe factors associated with antithyroid drug (ATD) treatment
during gestation among women with hyperthyroidism in pregnancy, ii) to investigate the impact of ATD
treatment during gestation on pregnancy outcomes.
Methods: Women with hyperthyroidism in pregnancy and ATD treatments were identified through linkage of
three national registries (2008-2018): The Medical Birth Registry of Norway, the Norwegian Prescription
Registry and the Norwegian Patient Registry. Pregnancies were categorized as ATD treated or untreated based
on filled prescriptions indicating ATD exposure during pregnancy. ATD treatment was examined by trimester
(T1, T2/T3) and by substance carbimazole (CMZ), propylthiouracil (PTU) and by both CMZ/PTU. Generalized
estimating equations analysis with a robust variance estimator was used to estimate adjusted odds ratio (aOR)
and adjusted standardized mean difference (aSMD) with 95% confidence interval (CI).
Results: We identified 1699 pregnancies with hyperthyroidism during gestation. Hyperthyroidism was treated
with ATD in 44.4% of the pregnancies, while 55.6% were untreated. Pregnant women treated with ATD had
more often asthma compared to untreated women. Prenatal exposure to CMZ was associated with increased risk
of preterm birth (aOR 1.8, 95% CI 1.1-2.8) whereas PTU exposure in the first trimester was associated with an
increased risk of cardiac malformations (aOR 9.0, 95% CI 1.8-44.7). There was no association between ATD
treatment in pregnancy and maternal preeclampsia (aOR 0.8, 95% CI 0.4-1.3) and gestational hypertension (aOR
0.9, 95% CI 0.5-1.8).
Conclusion: This nationwide registry study found an association between treatment with carbimazole and increased
risk of preterm birth. Exposure to propylthiouracil in the first trimester was associated with an increased
risk of cardiac malformations. These findings should be interpreted in light of international findings on the risk
of untreated hyperthyroidism and the potential risk of ATD treatment for the mother and child.
Downloads
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2021 El Khalil Nebghouha
This work is licensed under a Creative Commons Attribution 4.0 International License.
Norsk Epidemiologi licenses all content of the journal under a Creative Commons Attribution (CC-BY) licence. This means, among other things, that anyone is free to copy and distribute the content, as long as they give proper credit to the author(s) and the journal. For further information, see Creative Commons website for human readable or lawyer readable versions.
Authors who publish with this journal agree to the following terms:
1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
