OBJECTIVE

Hypothyroidism in pregnant women must be carefully managed to prevent complications. The aim of this study was to evaluate compliance with clinical recommendations for the monitoring and treatment of hypothyroidism in pregnant women and to assess the clinical action upon each biochemical monitoring at different time points in pregnancy.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Pregnant women with known hypothyroidism in the North Denmark Region, 2022-2024, who were managed in the Departments of Endocrinology.

MEASUREMENTS

Medical records were reviewed for information on biochemical monitoring of thyroid-stimulating hormone (TSH) and Levothyroxine (L-T4) treatment in the pregnancy. The primary study endpoint was the frequency of biochemical monitoring and dose adjustments of L-T4.

RESULTS

Altogether 175 pregnant women with hypothyroidism treated with L-T4 before the pregnancy were studied. Biochemical monitoring of TSH in the pregnancy was performed one to 12 times (median 7 times). When considered until and including the 12th week of pregnancy, the number of women with dose adjustment following biochemical control was 84 of 166 (50.6% (95% CI: 42.7%-58.4%)), whereas from the 13th to 24th week it was 35 of 164 (21.3% (95% CI: 15.3%-28.4%)), and from the 25th week of pregnancy and onwards it was 17 of 165 (10.3% (95% CI: 6.1%-16.0%)).

CONCLUSION

In a Danish regional cohort of pregnant women with hypothyroidism, biochemical monitoring of thyroid function was often performed and was mostly followed by a change in the dose of L-T4 in early pregnancy ( ~ 50% of the women) and rarely in late pregnancy ( ~ 10% of the women).