Pregnancy after breast cancer: Results from a prospective cohort of young women with breast cancer.

BACKGROUND: Many young women with newly diagnosed breast cancer are interested in future pregnancies. Prospective data regarding fertility interest and reproductive patterns after diagnosis are needed to counsel patients. METHODS: The Young Women's Breast Cancer Study is a multicenter, prospective cohort of women who were diagnosed with breast cancer at age ≤40 years between 2006 and 2016. Women complete surveys at baseline, every 6 months for 3 years, then annually. Here, the authors describe fertility interest and pregnancies within 5 years of diagnosis for women with stage 0 through III breast cancer. RESULTS: Of 1026 eligible participants, 368 (36%) reported interest in future biologic children at least once within 5 years after diagnosis, including 16% at 5 years after diagnosis. Among 130 women who attempted to become pregnant, 90 (69.2%) conceived; and, among 896 women who did not attempt to conceive, 18 (2.0%) became pregnant, with a total of 152 pregnancies resulting in 91 live births. Factors associated with pregnancy included younger versus older age at diagnosis (aged ≤30 vs 36-40 years: odds ratio [OR], 6.63; 95% CI, 3.18-13.83; P < .0001; aged 31-35 vs 36-40 years: OR, 5.86; 95% CI, 3.37-10.17; P < .0001) and being nulliparous versus parous (OR, 2.66; 95% CI, 1.56-4.53; P = .001). The receipt of endocrine therapy versus no endocrine therapy (OR, 0.35; 95% CI, 0.20-0.59; P = .001) was inversely associated with pregnancy. CONCLUSIONS: Many women remain interested in future fertility in the 4 years after a breast cancer diagnosis, indicating that longitudinal fertility discussions are needed. Although a minority of those interested in having children attempted to become pregnant in the first 5 years, most who attempted to conceive did so and had live births.