Nationwide cohort study of childhood cancer risk after assisted reproductive technology in Denmark

A nationwide cohort study in Denmark examined assocations between assisted reproductive technology (ART) and childhood cancer overall and by ART modality and cancer type. The cohort consisted of 1 086 136 children live-born from 1996 to 2012, of whom 37 228 (3.4%) were conceived using ART, with follow-up through 2023. During a median follow-up of 20 years, 3736 cancers occurred. Compared with non-ART births (incidence rate 18.3 per 100 000 person-years), children conceived using ART had higher cancer incidence rate (23.6 per 100 000 person-years; HR 1.26; 95% CI 1.97-1.48). Rates were higher after frozen embryo transfer and intracytoplasmic sperm injection, but not after in vitro fertilization (IVF). Frozen embryo transfer was associated with leukemia, lymphomas, and soft tissue sarcomas; intracytoplasmic sperm injection was associated with lymphomas, soft tissue sarcomas, and central nervous system neoplasms; no associations were observed for IVF. The authors conclude tha ART, particularly frozen embryo transfer and intracytoplasmic sperm injection, was associated with increased childhood cancer risk, but absolute risks were low.