Loading ...

Elevated eosinophil levels at or near the time of conception were independently associated with more frequent asthma exacerbations during pregnancy, based on new data presented at the American Thoracic Society (ATS) 2026 International Conference.

Pregnancy is complicated by asthma, but clinicians have limited understanding of which patients are more likely to experience exacerbations during pregnancy, said lead author Christian Cardillo, MD, current pulmonology and critical care fellow at the Temple Lung Center, Philadelphia, who will join the center as an assistant professor at the Lewis Katz School of Medicine at Temple University this summer.

Previous research in nonpregnant populations has suggested that eosinophilic inflammation may be associated with a more severe and exacerbation-prone asthma phenotype, but the significance in pregnant populations has not been well studied, Cardillo said. “We aimed to evaluate whether eosinophil counts could serve as a clinically useful marker of exacerbation risk during pregnancy,” he explained.

Cardillo and colleagues reviewed data from 31 pregnant patients with physician-diagnosed asthma who were receiving pregnancy care at a single center. They evaluated associations between periconception eosinophil counts and gestational asthma exacerbation frequency using a multivariate linear regression analysis.

Overall, higher absolute eosinophil count (defined per 100 cells/μL) was independently associated with increased frequency of asthma exacerbations during pregnancy. Each 100 cells/μL was associated with 0.20 additional exacerbations after controlling for factors including age, BMI, active smoking status, maintenance controller therapy, and asthma exacerbation history prior to conception (adjusted beta value, 0.20, 95% CI, 0.12-0.28, P < .001).

The results support the idea that eosinophilic inflammation remains clinically relevant during pregnancy despite the complex physiologic and immunologic changes patients experience, said Cardillo. “While the association itself was not entirely unexpected, the consistency of the relationship across the cohort reinforced the potential importance of eosinophils as a marker of disease activity in this population,” he said.

Simple Risk Assessment

The findings were limited by several factors including the small sample size and retrospective design, and additional prospective studies are needed to validate the results in larger and more diverse patient populations, Cardillo noted.

However, the results suggest that periconception eosinophil counts may help identify pregnant patients with asthma who are at increased risk for exacerbations, he said. Given the low cost and widespread availability of eosinophil testing, it may serve as an additional tool to assess risk and guide closer monitoring or earlier asthma therapy optimization during pregnancy, he noted.

“Future research should also explore whether eosinophil-directed treatment strategies, including the potential role of biologic therapies, can improve asthma control and pregnancy-related outcomes,” he added.

Help for Vulnerable Patients

High blood eosinophil levels, a marker of type 2 inflammation, have been associated with poor outcomes in asthma, COPD, and bronchiectasis, but information regarding the relationship between eosinophil levels measured during the periconception period and future asthma exacerbations during pregnancy is limited, said Diego Maselli, MD, division chief of Pulmonary Diseases and Critical Care Medicine and professor of medicine at the University of Texas Health at San Antonio. “Identifying patients at higher risk is particularly important in this already vulnerable population, where exacerbations may negatively affect both maternal and fetal health,” said Maselli, who was not involved in the study.

The new study findings support the need for attention to pregnant patients with asthma and elevated blood eosinophil counts, particularly above 300 cells/μL, as they may be at increased risk for future exacerbations, said Maselli. “Blood eosinophil counts may help identify patients who could benefit from closer monitoring and optimization of asthma management during pregnancy,” he added.

The findings also are consistent with previous studies showing that elevated blood eosinophil counts are associated with increased exacerbation risk in asthma and underscore the association between type 2 inflammation and poor outcomes across a broad range of airway diseases and patient populations, Maselli said.

Larger, prospective studies are needed to confirm the current study findings, and future studies also should evaluate whether targeted interventions in at-risk patients can reduce exacerbations and improve maternal and fetal outcomes, he noted.

The study received no outside funding. Cardillo had no financial conflicts to disclose. Maselli had no financial conflicts to disclose.