In the Journals

Radioactive iodine treatment not linked to adverse pregnancy outcomes at 6 months

Photo of Gi Hyeon Seo
Gi Hyeon Seo

Radioactive iodine treatment following a thyroidectomy was not associated with adverse pregnancy outcomes when conception occurred 6 months or longer after treatment, according to study results published in JAMA Internal Medicine.

“Current guidelines recommend that women delay pregnancy for 6 to 12 months after the receipt of radioactive iodine treatment following thyroidectomy for differentiated thyroid carcinoma,” Gi Hyeon Seo, MD, of the Health Insurance Review and Assessment Service in Seoul, South Korea, told Healio Primary Care. “Although concerns exist regarding the risks associated with pregnancy after [radioactive iodine treatment], no large-scale study to date has investigated the association between [radioactive iodine treatment] and pregnancy outcomes.”

Researchers conducted a population-based cohort study of women aged 20 to 49 years who underwent thyroidectomy for differentiated thyroid carcinoma. They compared outcomes in those who received radioactive iodine treatment after surgery to those who did not.

A total of 111,459 women with a mean age of 39.8 years at the time of thyroidectomy, 10,842 (9.7%) of whom became pregnant, were included in the study.

Radioactive iodine treatment following a thyroidectomy was not associated with adverse pregnancy outcomes when conception occurred 6 months or longer after treatment, according to study results published in JAMA Internal Medicine.

Among those who did and did not receive radioactive iodine treatment, researchers observed similar rates of abortion (30.7% vs. 32.1%), preterm delivery (12.8% vs. 12.9%) and congenital malformation (8.9% vs. 9%).

In a subgroup analysis based on time between receiving radioactive iodine therapy and conception, the rate of congenital malformation was 13.3% from 0 to 5 months after treatment, compared with 8.5% in the control group. After 6 months, rates were similar in the treatment and control groups 7.9% vs. 7.6%.

Compared with those who conceived 12 to 23 months after receiving radioactive iodine treatment, those who conceived 0 to 5 months after treatment had a significantly increased risk for congenital malformation (adjusted OR = 1.74; 95% CI, 1.01-2.97).

The rate of abortion — both spontaneous and induced — was also significantly higher when women conceived closer to the time they received treatment, with a rate of 60.6% for 0 to 5 months, 30.1% for 6 to 11 months, 27.4% for 12 to 23 months and 31.9% for 24 months or longer.

“These large-scale real-world data suggest that radioactive iodine treatment after thyroidectomy is not associated with an increase in adverse pregnancy outcomes when conception occurs after a 6-month waiting period,” Seo said. “Patients can be reassured that, after a 6-month waiting period, radioactive iodine treatment does not increase adverse pregnancy outcomes compared with surgery alone.” – by Erin Michael

Disclosures: The authors report no relevant financial disclosures.

Photo of Gi Hyeon Seo
Gi Hyeon Seo

Radioactive iodine treatment following a thyroidectomy was not associated with adverse pregnancy outcomes when conception occurred 6 months or longer after treatment, according to study results published in JAMA Internal Medicine.

“Current guidelines recommend that women delay pregnancy for 6 to 12 months after the receipt of radioactive iodine treatment following thyroidectomy for differentiated thyroid carcinoma,” Gi Hyeon Seo, MD, of the Health Insurance Review and Assessment Service in Seoul, South Korea, told Healio Primary Care. “Although concerns exist regarding the risks associated with pregnancy after [radioactive iodine treatment], no large-scale study to date has investigated the association between [radioactive iodine treatment] and pregnancy outcomes.”

Researchers conducted a population-based cohort study of women aged 20 to 49 years who underwent thyroidectomy for differentiated thyroid carcinoma. They compared outcomes in those who received radioactive iodine treatment after surgery to those who did not.

A total of 111,459 women with a mean age of 39.8 years at the time of thyroidectomy, 10,842 (9.7%) of whom became pregnant, were included in the study.

Radioactive iodine treatment following a thyroidectomy was not associated with adverse pregnancy outcomes when conception occurred 6 months or longer after treatment, according to study results published in JAMA Internal Medicine.

Among those who did and did not receive radioactive iodine treatment, researchers observed similar rates of abortion (30.7% vs. 32.1%), preterm delivery (12.8% vs. 12.9%) and congenital malformation (8.9% vs. 9%).

In a subgroup analysis based on time between receiving radioactive iodine therapy and conception, the rate of congenital malformation was 13.3% from 0 to 5 months after treatment, compared with 8.5% in the control group. After 6 months, rates were similar in the treatment and control groups 7.9% vs. 7.6%.

Compared with those who conceived 12 to 23 months after receiving radioactive iodine treatment, those who conceived 0 to 5 months after treatment had a significantly increased risk for congenital malformation (adjusted OR = 1.74; 95% CI, 1.01-2.97).

The rate of abortion — both spontaneous and induced — was also significantly higher when women conceived closer to the time they received treatment, with a rate of 60.6% for 0 to 5 months, 30.1% for 6 to 11 months, 27.4% for 12 to 23 months and 31.9% for 24 months or longer.

“These large-scale real-world data suggest that radioactive iodine treatment after thyroidectomy is not associated with an increase in adverse pregnancy outcomes when conception occurs after a 6-month waiting period,” Seo said. “Patients can be reassured that, after a 6-month waiting period, radioactive iodine treatment does not increase adverse pregnancy outcomes compared with surgery alone.” – by Erin Michael

Disclosures: The authors report no relevant financial disclosures.