Radioiodine treatment complications to the mother and child in patients with differentiated thyroid carcinoma.

Radioiodine ((131)I) has been widely used in the treatment of differentiated thyroid carcinoma (DTC). Since radiation can carry a known risk of mutagenic abnormalities, we decided to study the outcome of pregnancy in females with DTC and evaluate the genetic risks and health status of their offspring. We retrospectively studied the medical records of these patients in our Institute from 1999 to 2004. A total of 1110 women were hospitalized for treatment with high doses of (131)I, at least 3700MBq. During this period, 653 of these women were in their reproductive period. A hundred of them who had at least one pregnancy after (131)I treatment, were studied. These women had a total of 126 pregnancies (1-6 pregnancies each) after treatment and 101 pregnancies before treatment. We also reviewed the (131)I dose administered last, as well as the cumulative dose of (131)I. Our results show that the incidence of abortions before (131)I treatment was 16.83% (all were spontaneous abortions) and increased to 26.19% after (131)I treatment (15.87% induced and 10.3% spontaneous abortions). Spontaneous abortions were decreased. There was no significant difference between the mean last (131)I dose and the cumulative dose in patients with or without a history of abortions. Mean interval between the last dose of (131)I treatment and abortions versus the last dose and live child births showed a significant difference. All children had normal birth weight. Three congenital anomalies: Down's syndrome, cardiac abnormalities and macrocephaly were diagnosed. Three episodes of intrauterine death were also recorded. In conclusion, our findings indicate that in women with DTC, treated with high doses of(131)I: a) There was no evidence of increased spontaneous abortions, b) Increasing the interval between the last dose of (131)I treatment and time to pregnancy might be beneficial for decreasing the entire risk of abortions and c) It appears that (131)I treatment had no obvious adverse effects on the risk of congenital anomalies.