Thyroid function testing in women who had a stillbirth

ContextThyroid dysfunction is thought to be associated with stillbirth. Therefore, thyroid function is often recommended in the diagnostic investigations for stillbirth.

ObjectiveWe aimed to evaluate the added value of thyroid function testing in the diagnostic investigations for stillbirth.

Design and patientsA nationwide multicentre prospective cohort study in 1025 women who suffered stillbirth >20 weeks of gestation performed between 2002 and 2008. In each woman, an extensive diagnostic work-up was performed, including placental examination and autopsy. TSH and FT4 values below the 25th percentile or above the 975th percentile according local laboratory reference values were regarded as abnormal. Women with a history of thyroid disease were evaluated separately.

Main outcome measuresThyroid function abnormalities in women with stillbirth.

ResultsOf 1025 included women, 21 had a history of thyroid disease (2%). In the 875 with TSH and FT4 results and no history of thyroid disease, 10% had hypothyroxinemia, 46% subclinical hypothyroidism, 16% overt hypothyroidism and 15% subclinical hyperthyroidism. Women with a subclinical hyperthyroidism more often had a foetal death caused by foetal hydrops: 23% vs 29% (adjusted OR 103, 95% CI 25-42).

ConclusionsWomen with a stillbirth had a slightly higher prevalence of overt hypothyroidism, subclinical hypothyroidism and hypothyroxinaemia compared to previous studies on thyroid dysfunction in pregnant women. Given the absence of a strong associations with the cause of stillbirth, and no demonstrated beneficial effects of treating thyroid dysfunction in these women, routine screening after stillbirth is not justified.