ABSTRACT
Objectives: To evaluate risks of preterm birth and severe
maternal morbidity (SMM) in female adolescent and young adult cancer
survivors 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 U.S.
Sample: Female with live births from 2000 to 2019 within a
de-identified U.S. administrative health claims dataset
Methods: Log-binomial regression models estimated relative
risks of preterm birth and SMM by cancer status and tested for effect
modification. Causal mediation analysis based on a counterfactual
approach evaluated the proportions explained by maternal comorbidity.
Main Outcome Measures: SMM, preterm birth
Results: Among 46,064 cancer survivors, 2,440 singleton births,
214 multiple births, and 2,590 linked newborns occurred after cancer. In
singleton births, preterm birth incidence was 14.8% in cancer survivors
versus 12.4% in females without cancer (aRR 1.19, 95%CI 1.06-1.34);
SMM incidence 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 preterm birth and 30% of the association
between cancer and SMM was mediated by maternal comorbidities.
Associations between cancer and outcomes did not differ between ART and
non-ART births.
Conclusion: Preterm birth and SMM risks were modestly increased
after cancer. Significant proportions of elevated risks may be due to
increased comorbidities. Prevention and treatment of comorbidities
provides an opportunity to improve perinatal outcomes among cancer
survivors.