Conference Coverage

High Rates of Severe Maternal Morbidity, Preterm Birth in Pregnant Individuals with Sickle Cell Disease in the United States

Edited by:
Kate Young

Key Highlights

  • Pregnant individuals with sickle cell disease (SCD) had a 25% rate of severe maternal morbidity (SMM) versus 2.4% among those without SCD.
  • Adjusted odds of SMM remained significantly elevated even after excluding sickle cell crisis and transfusion from SMM definitions.
  • Preterm birth risks were 1.66–1.72 times higher in individuals with SCD compared with controls.
  • Findings derive from >2.8 million deliveries across all U.S. states from 2020–2024.

Pregnant individuals with sickle cell disease continue to experience substantially worse maternal outcomes compared with the general obstetric population, according to new nationwide evidence presented at the 67th ASH Annual Meeting and Exposition in Orlando, FL,. Leveraging a large contemporary electronic health record (EHR) dataset, researchers evaluated modern trends in severe maternal morbidity and preterm birth, providing one of the most comprehensive assessments of maternal risk in SCD to date.

The investigators conducted a retrospective cohort study using Epic Cosmos, a nationwide EHR database capturing clinical information from more than 300 million patients across 1748 U.S. hospitals. All delivery encounters from 2020–2024 were eligible. For patients with multiple deliveries, one encounter was randomly selected to avoid duplication.

SCD was defined by ≥3 encounters with SCD-related codes. Severe maternal morbidity (SMM) followed the CDC’s algorithm of 16 diagnostic conditions and 5 procedures. A secondary analysis excluded sickle cell crisis and transfusion to better assess SMM unrelated to baseline disease burden. The team used multivariable logistic regression to estimate adjusted odds ratios while controlling for year, gestational age, pregnancy-related conditions, and socioeconomic variables. Preterm birth—defined as <37 weeks—was compared between SCD and non-SCD populations, with analyses stratified by Black race.

Study Findings

Across the study period, 2679 deliveries occurred among individuals with SCD compared with more than 2.8 million deliveries among individuals without SCD. Among Black or African American patients, 0.5% had SCD, aligning with national prevalence patterns.

SMM occurred in 25% of deliveries among individuals with SCD versus 2.4% among controls. This corresponded to an adjusted odds ratio (aOR) of 8.67 (95% CI, 7.76–9.67; P < .001). Even when sickle cell crisis and transfusion were removed from the definition, SMM remained significantly elevated (aOR, 4.61, 95% CI, 4.06–5.23; P < .001).

When analyses were limited to Black patients, SMM risk persisted at similarly high levels—an aOR of 8.97 (95% CI, 7.98–10.07; P < .001) under the full SMM definition, and 3.47 (95% CI, 2.87–4.18; P < .001) in the restricted definition.

Preterm birth also occurred more frequently among individuals with SCD. Compared with controls, the adjusted odds of preterm birth were 1.66 times higher (95% CI, 1.48–1.86; P < .001). This association remained significant when restricted to Black patients (aOR, 1.72, 95% CI, 1.52–1.93; P < .001).

Clinical Implications

The authors note that contemporary EHR-based data confirm persistently high maternal risks for pregnant individuals with SCD, even after adjustment for key confounders and regardless of racial stratification. The addition of preterm birth findings underscores another dimension of adverse obstetric outcomes within this population. According to the researchers, these results reinforce the need to prioritize maternal health interventions and surveillance strategies tailored to SCD.

Expert Commentary

“This is the most comprehensive and current EHR-based analysis of maternal outcomes in SCD, including data from the post-COVID-19 era,” the researchers concluded. “Future directions include leveraging Cosmos to examine additional fetal and maternal outcomes, evaluate transfusion burden, and explore associations with baseline lab features. Our results reinforce the ongoing urgency to improve maternal outcomes in this high-risk population.”

Reference
Cheng A, Dysart K, Burris H, Lanzkron S, Roe A. High rates of severe maternal morbidity and preterm birth among pregnant individuals with sickle cell disease, a nationwide study from 2020–2024. Presented at: 67th ASH Annual Meeting and Exposition in Orlando, FL. December 6, 2025. https://submit.hematology.org/program/presentation/671210