ESR1 and cancer: There was no association of the number of births as a continuous variable with ER/PR+HER2+ cancers; however, women with two births had a significantly higher risk than women with one birth (HR = 1.39, 95% CI 1.02–1.90), but patients with three or more births had no significant difference in risk than patients with 1 birth (HR = 0.92, 95% CI 0.64–1.32).