Live birth outcomes after adolescent and young adult breast cancer.

Reproductive outcomes are an important survivorship concern for women diagnosed with cancer as adolescents and young adults (AYAs). We examined the incidence of live birth and the prevalence of adverse birth outcomes according to tumor and treatment characteristics among AYAs with breast cancer. Women diagnosed with breast cancer at ages 15-39 during 2000-2013 were identified using the North Carolina Central Cancer Registry (n = 4,978). Cancer registry records were linked to state birth certificate files from 2000 to 2014 to identify births to women with and without a breast cancer history. The breast cancer cohort was followed until live birth, death, age 46, or December 31, 2014, whichever occurred first. For each birth to breast cancer survivors (n = 338), we sampled 20 births to women without a recorded cancer diagnosis, with frequency matching on maternal age and year of delivery. The cumulative incidence of live births after breast cancer was 8% at 10 years. Births were less common among women treated with chemotherapy. Overall, the prevalence of preterm birth, low birth weight, small-for-gestational age (SGA) and Cesarean delivery did not differ substantially between births to women with and without breast cancer. However, births to women with ER-negative disease were more likely to be preterm (PR = 1.84; 95% CI: 1.11-3.06). In this population-based study, <10% of AYA breast cancer survivors had a live birth within 10 years of their diagnosis. The increase in risk of preterm delivery among ER-negative survivors in our cohort warrants further investigation in larger studies.