ESPE Abstracts

Introduction: Maternal thyroid disease is considered as a risk factor for abnormal thyroid function at birth as well as for long-term morbidity in offspring. The potential harmful effects on the neonate had led to the clinical practice of thyroid function assessment in infants born to mothers with thyroid disease during pregnancy, despite well-established newborn screening programs with include congenital hypothyroidism screening. We evaluated the usefulness of routine thyroid function tests, in addition to newborn screening programs for congenital hypothyroidism, for every newborn of a mother with thyroid dysfunction.

Methods: Data were collected retrospectively from the medical files of mothers diagnosed with thyroid disease and their infants (701 mother–neonate pairs). all mothers with diagnosis of thyroid disease that gave birth between the years 2016-2019 in our medical center were included.

Results: Hypothyroidism was the most common maternal diagnosis (91.4%). Among which 48.7% had Hashimoto's thyroiditis. Hyperthyroidism was diagnosed in 8.6% of the cohort, —of whom 71.6% had a diagnosis of Graves' disease. None of the newborns was diagnosed with congenital hypothyroidism in the screening program. Thyroid-stimulating hormone was >10 mIU/l in 14.6% and >20 mUI/l in 2.2%, all had free thyroxine within normal range. Four infants were diagnosed with thyroid disease: hypothyroidism (3) and neonatal Graves' disease (1). Two neonates had congenital hypothyroidism not related to maternal thyroid disease, and one had transient familial congenital hypothyroidism.

Conclusions: Thyroid function testing for all newborns of mothers with thyroid dysfunction seems redundant. However, in cases of congenital hypothyroidism in siblings, a stricter approach is indicated and in maternal Graves' disease, thyroid function testing on day 2–3 of life is recommended.