- The risk for childhood cancer was small but statistically significant in those born after the use of frozen embryo transfer compared with children born to fertile women.
- No significant increase in risk was observed with the use of other assisted reproductive technology.
Why this matters
- The number of children born after the use of fertility treatment is increasing worldwide.
- There is no clarity whether fertility treatment and the use of specific drugs/procedures or the underlying infertility increase cancer risk in children.
- A retrospective cohort study of 1,085,172 children born to fertile women (n=910,291) and born to women requiring fertility assistance (n=174,881).
- Of 174,881 children, 89,981 were born after the use of fertility treatment and 84,900 were born without the use of fertility treatment.
- Funding: None disclosed.
- After 12.2 million person-years of follow-up, the incidence rate of childhood cancer was 17.6 per 100,000 in women with infertility vs 17.5 per 100,000 in fertile women (HR, 1.02; 95% CI, 0.91-1.15; incidence rate difference, 0.1 [95% CI, −2.0 to 2.2] per 100,000).
- Children born after the use of frozen embryo transfer vs those born to fertile women were at an increased risk for cancer (HR, 2.43; 95% CI, 1.44-4.11; incidence rate difference, 26.9 [95% CI, 2.8-51.0] per 100,000).
- Risk for leukaemia (HR, 2.87; 95% CI, 1.19-6.93; incidence rate difference, 10.1 [95% CI, −4.0 to 24.2] per 100,000) and sympathetic nervous system tumours (HR, 7.82; 95% CI, 2.47-24.70) was higher in children born after the use of frozen embryo transfer vs those born to fertile women.
- No difference was observed between other fertility treatment and childhood cancer.
- Retrospective design.
- Possible risk for unknown or residual confounding.