Maternal Thyroid Diseases, Medication Use and Childhood Cancer Risks in Offspring: A Population-Based Cohort Study in Denmark.

Thyroid diseases are common among women of reproductive age and may be related to childhood cancer among offspring, though the evidence is inconsistent. Using Danish registries, we conducted a population-based case-control study to investigate the relationship between maternal thyroid diseases and medication use and childhood cancer among offspring. Cases (N = 2521) diagnosed between 1973 and 2016 were ascertained from the Danish Cancer Registry, and controls (N = 63,014) were randomly selected from the Central Population Registry and matched on sex and date of birth. Information on diagnoses and prescriptions was obtained from the National Patient Register and the National Prescription Register, respectively. Conditional logistic regression was applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Goiter was associated with any cancer (OR = 2.08, 95% CI: 1.44, 3.00), leukemia (OR = 2.18, 95% CI: 1.13, 4.18), acute lymphoblastic leukemia (OR = 2.12, 95% CI: 1.02, 4.42), and lymphoma (OR = 3.06, 95% CI = 1.20, 7.82). There was no observed association between childhood cancer and maternal hypothyroidism or hyperthyroidism; however, these results were likely underpowered. No increased risk of cancer was observed for maternal thyroid medication use. Though the small sample size must be considered, the elevated risk of cancer with maternal thyroid diseases, especially goiter, was notable.