Risk of cancer in the offspring of women who underwent ovarian stimulation for IVF

Over the past decade attention has been increasingly focused on the long-term health effects of assisted reproductive technologies (ART), such as IVF, in both women and their offspring. To determine the risk of cancer in children conceived by IVF we used a large population-based historical cohort that was initially designed to examine the risk of gynaecological disorders in women who underwent IVF.Children were included in the exposed group if they were conceived by IVF or other related fertility techniques (n=9484). The unexposed group consisted of 7532 children whose mothers were diagnosed with subfertility disorders but who were conceived naturally. All cohort members were asked to complete a mailed questionnaire that inquired about reproductive variables and cancer in the offspring (response rate 66.9%).During an average follow-up period of 6.0 years, 16 cancers were observed in the exposed and unexposed group combined, whereas 15.5 were expected [standardized incidence ratio (SIR) = 1.0; 95% confidence interval (95% CI) 0.6-1.7]. A direct comparison between children conceived after ART and naturally conceived children revealed no increased risk for childhood malignancies [risk ratio (RR) = 0.8; 95% CI 0.3-2.3].Despite the small numbers of observed cancer cases, these findings demonstrate that children conceived by ART have no greatly increased risk of cancer during childhood compared with the general population and the internal reference group.