Levothyroxine Treatment of Pregnant Women with Hypothyroidism: Retrospective Analysis of a US Claims Database

BACKGROUND: Approximately 2–4% of women of reproductive age have hypothyroidism. This study characterizes pregnant women with hypothyroidism and examines adherence to guidelines during pregnancy. METHODS: Women age 18 to 49 who were pregnant in 2014 and identified with hypothyroidism (N = 3448) were included in the retrospective study. The analyses examined differences in characteristics and comorbidities between pregnant women treated with levothyroxine and untreated women and adherence to guidelines by measuring thyroid-stimulating hormone (TSH) target achievement for women treated with levothyroxine. RESULTS: The average age was 32.76 years, and the median TSH value was 1.97 mIU/l. Compared with untreated pregnant women, pregnant women treated with levothyroxine were significantly younger, had a lower Charlson Comorbidity Index score and had lower rates of comorbid type 2 diabetes and migraines. Among women treated with levothyroxine, 52.61% had a last recorded TSH value consistent with American Thyroid Association (ATA) guidelines, 23.85% were undertreated, 1.03% were overtreated, and 22.52% did not have TSH monitored during their pregnancy. CONCLUSIONS: A large percentage of pregnant women, including many treated with levothyroxine, was not treated in a manner consistent with clinical guidelines. Additionally, there were significant differences in general health and comorbidities between pregnant women treated with levothyroxine and those untreated.