Infertility Treatments Resulting in Twin Pregnancy: Does It Increase the Risk for Future Childhood Malignancy

Background: Controversy exists in the literature regarding the possible association between infertility treatments in singleton pregnancies and long-term risk for childhood malignancy. Data regarding infertility treatments in twins and long-term childhood malignancies are scarce. Objective: We sought to investigate whether twins conceived following infertility treatments are at an increased risk for childhood malignancy. Study design: A population-based retrospective cohort study, comparing the risk for future childhood malignancy in twins conceived by infertility treatments (in vitro fertilization and ovulation induction) and those who were conceived spontaneously. Deliveries occurred between the years 1991 and 2021 in a tertiary medical center. A Kaplan-Meier survival curve was used to compare the cumulative incidence of childhood malignancies, and a Cox proportional hazards model was constructed to control for confounders. Results: During the study period, 11,986 twins met the inclusion criteria; 2910 (24.3%) were born following infertility treatments. No statistically significant differences were noted between the groups comparing the rate (per 1000) of childhood malignancies (2.0 in the infertility treatments group vs. 2.2 in the comparison group, OR 1.04, 95% CI 0.41-2.62; p = 0.93). Likewise, the cumulative incidence over time was comparable between the groups (log-rank test, p = 0.87). In a Cox regression model, controlling for maternal and gestational age, no significant differences in childhood malignancies were noted between the groups (adjusted HR = 0.82, 95% CI 0.49-1.39, p = 0.47). Conclusions: In our population, twins conceived following infertility treatments are not at an increased risk for childhood malignancies.