Radioiodine therapy and subsequent pregnancy

To evaluate abortion and fetal congenital anomaly rates in women previously submitted to radioiodine therapy for differentiated thyroid carcinoma.

A case-control study of 108 pregnant women, 48 cases whose pregnancies were evaluated after they had undergone radioiodine therapy for differentiated thyroid carcinoma, and the control group consisted of 60 healthy pregnant women.

Of a total of 66 pregnancies, 14 conceived within the first year, 51 one or more years after the last administration of 131I, the medical record of one patient was not available. The interval between the last radioiodine therapy administration and conception ranged from 1 month to 10 years. There were a total of 4 miscarriages, 2 of them for unknown reasons. There was one case of congenital anomaly and two preterms birth. Nine women presented the following pregnancy events: placental insufficiency, hypertensive crisis, placental detachment, risk of miscarriage, preterm labour and four miscarriages. No statistical difference was observed between the studied and control groups.

Radioiodine was followed by no significant increase in untoward effects in neither the pregnancy nor the offspring.