Maternal comorbidity and adverse perinatal outcomes in survivors of adolescent and young adult cancer: A cohort study.

OBJECTIVE: To evaluate risks of preterm birth (PTB) and severe maternal morbidity (SMM) in female survivors of adolescent and young adult cancer and assess maternal comorbidity as a potential mechanism. To determine whether associations differ by use of assisted reproductive technology (ART). DESIGN: Retrospective cohort. SETTING: Commercially insured females in the USA. SAMPLE: Females with live births from 2000-2019 within a de-identified US administrative health claims data set. METHODS: Log-binomial regression models estimated relative risks of PTB and SMM by cancer status and tested for effect modification. Causal mediation analysis evaluated the proportions explained by maternal comorbidity. MAIN OUTCOME MEASURES: PTB and SMM. RESULTS: Among 46 064 cancer survivors, 2440 singleton births, 214 multiple births and 2590 linked newborns occurred after cancer diagnosis. In singleton births, the incidence of PTB was 14.8% in cancer survivors versus 12.4% in females without cancer (aRR 1.19, 95% CI 1.06-1.34); the incidence of SMM was 3.9% in cancer survivors versus 2.4% in females without cancer (aRR 1.44, 95% CI 1.13-1.83). Cancer survivors had more maternal comorbidities before and during pregnancy; 26% of the association between cancer and PTB and 30% of the association between cancer and SMM was mediated by maternal comorbidities. Tests for effect modification of cancer status on perinatal outcomes by ART were non-significant. CONCLUSIONS: Preterm birth and SMM risks were modestly increased after cancer. Significant proportions of elevated risks may result from increased comorbidities. ART did not significantly modify the association between adolescent and young adult cancer and adverse perinatal outcomes. The prevention and treatment of comorbidities provides an opportunity to improve perinatal outcomes among cancer survivors.