BACKGROUND AND PURPOSE:

• Recommendations for pregnancy timing following radioactive iodine treatment (RAIT) after thyroidectomy for differentiated thyroid carcinoma suggest waiting 6 to 12 months
• Hye et al. (JAMA Intern Med., 2019) sought to ascertain whether RAIT was associated with an increase in adverse pregnancy outcomes and the appropriate interval to conception

METHODS:

• Population-based cohort study
• Setting
  • Health Insurance Review and Assessment database of South Korea
• Participants
  • Women 20-49 years
  • Underwent thyroidectomy for the treatment of differentiated thyroid carcinoma
• Cohorts
  • Surgery alone
  • Surgery followed by RAIT
• Study design and data analysis
  • Pregnancy outcomes data reviewed
  • Multivariate logistic regression models used to control for confounding
• Primary outcomes
  • Rates of abortion (both spontaneous and induced, as the database could not distinguish between the two)
  • Preterm delivery
  • Congenital malformation

RESULTS:

• 111,459 women included
  • Surgery alone: 53.4%
  • Surgery and RAIT: 46.6%
• Pregnancies: 9.7% | Mean age at conception: 33.3 years
• No significant differences for the following
  • Abortion | Preterm delivery | Congenital malformation
• Congenital malformations rates based on interval between RAIT and conception
  • 0 to 5 months: 13.3%
  • 6 to 11 months: 7.9%
  • 12 to 23 months: 8.3%
  • ≥24 months: 9.6%
• Congenital malformations were more likely in conceptions that occurred 0 to 5 months after RAIT compared with conceptions that occurred 12 to 23 months after RAIT
  • Adjusted odds ratio (OR) 1.74 (95% CI, 1.01 to 2.97; P = 0.04)
• Congenital malformations noted in the 0 to 5 month post RAIT cohort included
  • 6 CVS | 4 MSK | 3 urinary system | 1 each for CNS, respiratory system, lip and palate, and genital organs
• Abortion rates based on interval between RAIT and conception
  • 0 to 5 months: 60.6%
  • 6 to 11 months: 30.1%
  • 12 to 23 months: 27.4%
  • ≥24 months: 31.9%

CONCLUSION:

• This large-scale study demonstrated that RAIT was not associated with malformations and increased miscarriage if conception occurs ≥6 months following treatment

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Learn More – Primary Sources:

Association Between Pregnancy Outcomes and Radioactive Iodine Treatment After Thyroidectomy Among Women With Thyroid Cancer

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