Anaphylaxis and pregnancy: Epidemiology, elicitors, and recurrences.

Background: Anaphylaxis during pregnancy implies a risk to both mothers and newborns. However, limited data are available. Therefore, our aim is to explore patterns of hospital admissions diagnosed with anaphylaxis in pregnant women in France from 2012 to 2021, using a national hospital billing database and to evaluate potential determinants, trends and recurrences. Methods: Descriptive study using data from the French Program for the Medicalization of Information Systems, from 2012 to 2021. We included all patients hospitalized for anaphylaxis using International Classification of Diseases (ICD)-10 codes listed as a primary diagnosis. Two groups of patients were included: pregnant (PW) and non-pregnant women (NPW), adjusted by age. Severe anaphylaxis (SA) was defined based on the need of admissions in intensive care units. Sankey graphics were employed to visualize data related to recurrences. Results: During a nine-year study period, 37,962 female patients had 42,399 admissions due to anaphylaxis for all causes. We evaluated data from 734 admissions for anaphylaxis experienced by 653 PW. In both groups 65% of cases were unspecified anaphylaxis, with high number of recurrences. PW experienced higher proportion of SA (8.7%, 95%CI [6.8%, 11.1%]) and recurrences (1.51, 95%CI [1.3, 1,7]), compared with NPW. Most of SA in PW was triggered by drugs (23%, 95%CI [22.3%, 23.6%]). Different from NPW, no seasonal trend was observed in the PW group. From all 670 PW who experienced non-SA, 0.33% (95% CI 0.09-1.2) evolved with SA, and 0.92% (95% CI 0.42-1.99) were admitted for different etiologies in forthcoming admissions. Conclusion: Beyond providing a snapshot of characteristics of anaphylaxis during pregnancy in France, we were able to explore trends and recurrence of anaphylaxis in this population. Although further research is needed in the field, we strongly believe that the data presented contributed as a starting point of public health advancements to ensure quality of care of patients suffering from anaphylaxis.