EXPOSURE TO RADIOACTIVE I-131 FOR SCINTIGRAPHY OR THERAPY DOES NOT PRECLUDE PREGNANCY IN THYROID-CANCER PATIENTS

Radiation is known to be mutagenic. The aim of the present study was t o ascertain whether exposure to I-131 induces genetic damage, as asses sed by pregnancy outcomes and the health status of offspring of women previously exposed to I-131 during thyroid carcinoma treatment. Method s: Data on 2113 pregnancies were obtained by interviewing female patie nts treated for thyroid carcinoma who had not received any significant external radiation to the ovaries. Results: The incidence of miscarri ages was 11% before any treatment for thyroid cancer; this number incr eased slightly after surgery for thyroid cancer, both before (20%) and after (20%) I-131, but did not vary with the cumulative I-131 dose. M iscarriages were more frequent (40%) in the ten women who were treated with I-131 [mean dose: 3.8 GBq (108 mCi)] during the year preceding c onception. Incidences of stillbirth, preterm birth, low birth weight, congenital malformation and death during the first year of life were n ot significantly different before or after I-131 therapy. The incidenc e of thyroid disease and nonthyroidal malignancy was similar in childr en born either before or after their mothers were exposed to I-131. Co nclusion: With the exception of miscarriages, there is no evidence tha t exposure to radioiodine affects the outcome of subsequent pregnancie s and offspring. The question of whether an increased incidence of mis carriages within 1 yr of I-131 administration relates to gonadal irrad iation or to insufficient control of hormonal thyroid status remains t o be established.