Pregnancy alters the circulating B cell compartment in atopic asthmatic women, and transitional B cells are positively associated with the development of allergy manifestations in their progeny

Problem Maternal atopy is a risk factor for allergy. B cells are poorly studied in reproduction and atopy. We aimed to assess how pregnancy affects B cells in atopic women and whether B cells relate to allergic manifestations in offspring. Method of study Women with and without atopic asthma, pregnant and non‐pregnant were enrolled for the study, and circulating B cells were evaluated by flow cytometry, using CD19, CD27, CD38, IgD, and IgM. Results Compared to healthy non‐pregnant, atopic asthmatic non‐pregnant (ANP) women presented increased B cell counts, enlarged memory subsets, less transitional cells, and plasmablasts. Atopic asthmatic pregnant (AP) and healthy pregnant (HP) women showed similarities: reduced B cell counts and percentages, fewer memory cells, especially switched, and higher plasmablast percentages. Transitional B cell percentages were increased in AP women with allergic manifestations in their progeny. Conclusion Atopic asthmatic non‐pregnant women have a distinctive B cell compartment. B cells change in pregnancy, similarly in AP and HP women. The recognition that AP women with allergy in their progeny have a typical immune profile may help, in the future, the adoption of preventive measures to avoid the manifestation of allergic diseases in their newborns.