Thyroid function testing in women who had a stillbirth.

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Perinatal Medicine

Background:

• Thyroid dysfunction is suspected to be linked to stillbirth.
• Thyroid function tests are often part of stillbirth investigations.

Purpose of the Study:

• To assess the added value of thyroid function testing in stillbirth diagnostics.
• To evaluate the prevalence of thyroid function abnormalities in women experiencing stillbirth.

Main Methods:

• A nationwide prospective cohort study of 1025 women with stillbirth (>20 weeks gestation).
• Included extensive diagnostic work-up, placental examination, and autopsy.
• Defined abnormal thyroid function based on TSH and FT4 percentiles, with separate evaluation for women with prior thyroid disease.

Main Results:

• Among 875 women without a history of thyroid disease, 10% had hypothyroxinemia, 4.6% subclinical hypothyroidism, 1.6% overt hypothyroidism, and 1.5% subclinical hyperthyroidism.
• Subclinical hyperthyroidism was associated with fetal hydrops (adjusted OR 10.3).
• Prevalence of hypothyroidism and hypothyroxinemia was slightly higher than in previous studies of pregnant women.

Conclusions:

• Thyroid function abnormalities are present in some stillbirth cases but lack strong associations with stillbirth causes.
• No demonstrated benefits of treating thyroid dysfunction in these women were found.
• Routine thyroid function screening after stillbirth is not justified.