(737) Severe maternal morbidity among individuals with cancer in pregnancy and radiation treatment history

The study objective was to determine the odds of severe maternal morbidity (SMM) in pregnant individuals with cancer requiring radiation treatment pre-pregnancy compared to those without radiation treatment history.


Study Design:

This population-based, retrospective cohort study queried TriNetX, a research network containing de-identified electronic health data from over 155 million patients. Inclusion criteria were pregnant subjects 12-55 years diagnosed with cancer within one year prior to pregnancy, from 1/2015 to 8/2025. Two cohorts were derived: subjects with and without radiation treatment within one year prior to pregnancy. Cohorts were propensity score matched 1:1 on: age, race, ethnicity, diabetes, hypertension, hyperlipidemia, obesity, asthma, tobacco use, mental health disorder, chronic kidney disease, connective tissue disorder, cancer stage, surgery and chemotherapy. SMM was defined using the CDC’s 21 indicators and corresponding codes. The primary outcome was adjusted odds ratio (aOR) of composite SMM occurring in antepartum or postpartum periods (up to one year from pregnancy diagnosis). Secondary outcomes were aOR of SMM individual indicators. All analyses were conducted 8/2025 using the TriNetX platform.


Results:

After propensity score matching, subjects with cancer in pregnancy with and without radiation treatment pre-pregnancy (n=1065 for both) were analyzed (Table 1). Pregnant individuals with cancer and pre-pregnancy radiation history had higher odds of composite SMM (prevalence 26.0% versus 11.6%, aOR 2.89 (95% confidence interval (CI) 2.25-3.73)) compared to those without radiation history (Table 2). Air and thrombotic embolism emerged as the indicator with the highest odds (aOR 3.13 (95% CI 1.82-5.38)) (Table 2).


Conclusion:

A history of radiation oncology treatment within one year prior to pregnancy was associated with over 2.5 times increased odds of composite SMM. Further research is needed to explore the effect of radiation treatment history on the increased burden of maternal morbidity among patients with cancer in pregnancy.