Pregnancy and thyroid cancer: ultrasound study of foetal thyroid

Thyroid cancer is the most common endocrine malignancy, more frequently diagnosed in young women during childbearing age and approximately 10% of all thyroid cancers are diagnosed during pregnancy or in the early post-partum period. Thyroid cancer in young people has generally an excellent prognosis, and survival among women with thyroid cancer diagnosed during pregnancy may not differ from that in age-matched non-pregnant women with similar cancer. Pregnancy after treatment of thyroid carcinoma requires both maternal and foetal controls. Of utmost importance is to ensure adequate maintenance of maternal levels of levothyroxine, needed by both the foetal central nervous system for its normal maturation and the mother to avoid possible recurrence or spread of the disease. In the present investigation, to confirm normal foetal growth and foetal thyroid development, an ultrasound study of the foetal thyroid was performed in 40 full term pregnancies in 32 women receiving levothyroxine treatment for previously treated thyroid cancer. In patients undergoing either suppressive or substitutive levothyroxine treatment, foetal thyroid growth was noted to be normal in all the cases, newborn thyroid status was always normal, and the incidence of maternal morbidity was not influenced. In the present study group, pregnancy does not appear to compromise mother's disease-free interval, nor to be compromised by thyroid cancer treatment. Results of the present study confirm that regular adjustment of levothyroxine treatment is of utmost importance for both maternal and foetal well-being and that foetal thyroid ultrasound study may add useful and reassuring data about child well-being.