Two confounders namely consumption of OCs and Smoking should also be adjusted/matched or excluded in female cancers
The study says as follows :
"Observed first diagnosis of ovarian, breast, and corpus uteri cancer in cohort members were compared with age, sex, and period specific expectation. Standardised incidence ratios (SIRs) were calculated by use of age, sex, and period specific national incidence rates."
What our worry is that not only age and period specific incidence rates (Sex is obviously "female" as the cancers - namely, uterine, ovarian and breast - are female cancers), but other risk factors like Use of Oral contraceptives and Smoking should also be matched (if possible) before concluding that infertility treatments are a risk factor for these cancers.
Competing interests: No competing interests