Abstract
BACKGROUND/OBJECTIVES: Breast cancer may negatively affect later pregnancy and childbirth. We aimed to analyze the impact of previous breast cancer on obstetric outcomes in postdiagnosis pregnancies. METHODS: Insurance claims data in Southern Germany were used to identify breast cancer (BC) survivors with at least one subsequent delivery after cancer diagnosis between 2010 and 2020. In total, 74 BC survivors were compared to 222 age-matched controls with frequency matching on their age at their postdiagnosis delivery. RESULTS: Endocrine therapy was associated with a significantly lower probability of birth compared to BC survivors without endocrine therapy (HR 0.36; 95% CI 0.18-0.53; p < 0.0001). The risks of preterm birth, low birth weight (LBW), gestational diabetes, hypertensive disorders, and cesarean section were not significantly increased among BC survivors compared to healthy controls. BC survivors were at an increased risk for a small-for-gestational-age (SGA) fetus (OR 3.24; 95% CI 1.17-8.97, p = 0.03). Delivery in less than 2 years after diagnosis increased the risk for SGA (OR 5.73; 95% CI 1.37-24.02, p = 0.03) and LBW (OR 4.57; 95% CI 1.32-15.87, p = 0.02). CONCLUSIONS: Our findings are encouraging regarding the risks of preterm delivery, gestational diabetes, hypertensive disorders, and cesarean section to women who consider pregnancy after BC. Delivery in less than 2 years after diagnosis was associated with an increased risk for SGA and LBW.