Severe maternal morbidity up by fourfold in presence of CRC

Pregnant women with colorectal cancer (CRC) face a considerably increased likelihood of severe maternal morbidity (SMM), including disseminated intravascular coagulation, acute respiratory distress syndrome, and hysterectomy, among others, according to a study.

Analysis of large-scale data from the TriNetX platform involving expectant mothers between 12 and 55 showed that prevalence of the composite SMM outcome was 17.2 percent among those with CRC vs 4.5 percent among those without cancer history, yielding an odds ratio (OR) of 4.4 (95 percent confidence interval [CI], 3.7–5.2; p<0.001), reported one of the study authors Dr Shriddha Nayak from the Johns Hopkins University School of Medicine in Baltimore, Maryland, US. [SMFM 2025, abstract 98]

Looking at individual indicators of SMM, disseminated intravascular coagulation had the highest OR (4.3, 95 percent CI 3.4–5.4), followed by acute respiratory distress syndrome (OR, 3.7, 95 percent CI 3.1–4.5), air and thrombotic embolism (OR, 3.0, 95 percent CI, 2.1–4.2), and hysterectomy (OR, 3.0, 95 percent CI, 1.7–5.6), Nayak continued.

Puerperal cerebrovascular disorders, aneurysm and dissection, sepsis, and acute renal failure had ORs ranging from 2.0 to 2.9. Meanwhile, acute myocardial infarction, pulmonary edema/acute heart failure, and shock had ORs between 1.1 and 1.9.

Other SMM indicators such as cardiac arrest/ventricular fibrillation, conversion of cardiac rhythm, blood transfusion, eclampsia, temporary tracheostomy, and ventilation did not significantly differ between patients with CRC and those without cancer history.

“SMM includes unexpected outcomes from labour and delivery that can lead to significant short- and long-term health consequences and can be considered near misses for maternal mortality,” Nayak said.

The study is timely, given the American Cancer Society’s recent report on the increasing prevalence of early-onset cancers among young women, she added. “[The findings provide] useful information for preconception and pregnancy counselling and management.” [https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/2025-cancer-facts-figures.html]

Nayak pointed out that SMM indicators such acute respiratory distress syndrome, disseminated intravascular coagulation, air and thrombotic embolism, and hysterectomy are signals of interest. However, it is uncertain whether these indicators are independent or related, she said. “For example, a patient could have had a cancer debulking surgery at the time of delivery, which could have led to a hysterectomy or thromboembolism, or these events could have happened separately.”

The next step in the investigation is to validate the data using primary patient records, address additional confounding variables, explore other adverse perinatal outcomes, such as preterm delivery and pre-eclampsia, and investigate disparities among various groups, Nayak said.

“We hope insights from this study and future investigations can optimize clinical management for [pregnant] patients with colorectal or other malignancies,” she added.

The study included 7,570 patients in the CRC cohort (CRC diagnosis made 1 year prior to or up to 1 month after first instance of pregnancy) and 7,570 in the no-cancer cohort (absence of any malignant neoplasm before of up to 5 years after first instance of pregnancy). These patients were propensity-score matched based on age, race, ethnicity, hypertension, heart disease, diabetes, asthma, tobacco use, and obesity.

The primary outcome of SMM was defined according to the Centers for Disease Control and Prevention’s published list of 21 SMM indicators.

Study limitations included its retrospective design, the inability to validate diagnosis codes with the primary medical record, and the censoring of pregnancy outcomes and mortality data by TriNetX to protect patient privacy.