HealthDay News — Children born after use of assisted reproduction technology (ART) do not have an increased risk for any cancer, but those born after frozen-thawed embryo transfer (FET) have an increased risk for childhood cancer, according to a study published online September 1 in PLOS Medicine.

Nona Sargisian, from Sahlgrenska University Hospital in Gothenburg, Sweden, and colleagues conducted a registry-based cohort study using data from Denmark, Finland, Norway, and Sweden involving 7,944,248 children, of whom 2.2% were born after use of ART. The rates of any cancer and specific cancer groups were assessed for children born after each conception method.

The researchers found that after a mean follow-up of 9.9 and 12.5 years, the incidence rate of cancer before age 18 years was 19.3 and 16.7 per 100,000 person-years for children born after ART and spontaneous conception, respectively (adjusted hazard ratio, 1.08; 95% CI, 0.96 to 1.21; P =.18). Children born after FET had an increased cancer risk compared with fresh embryo transfer and spontaneous conception (adjusted hazard ratios, 1.59 [95% CI, 1.15 to 2.20; P =.005] and 1.65 [95% CI, 1.24 to 2.19; P = 0.001], respectively). The association was marginally attenuated after adjustment for macrosomia, birth weight, or major birth defects. There were higher risks observed for epithelial tumors and melanoma after any ART and of leukemia after FET.

“Although the absolute risk is low, these findings are important considering the increasing use of the freeze-all strategy,” the authors write.

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