Ovulation problems, ovarian endometriosis and impaired sperm quality may be factors underlying infertility and possibly predisposing to cancer diseases. Infertility therapies utilize products that alter the hormonal balance and may in theory increase the risk of cancer. Handling of gametes in the laboratory is also likely to influence gene regulation. Ovulation induction therapies may increase the risk of uterine cancer, and in vitro fertilization (IVF) therapies may increase ovarian tumors. Children born after IVF therapies seem to have a statistically elevated risk of cancer. Instead of risk ratios, the use of clear figures is recommended in patient information.