Background Women with asthma require fertility treatment more frequently and have longer time to pregnancy, together with a higher risk of pregnancy loss. Type 2 inflammatory cells (eosinophils, mast cells) undergo cyclic changes in the uterus. It is, however, unknown whether this contributes to impaired fertility among women with asthma.

Aim To explore if women with asthma have more inflammatory cells in the endometrium compared to non-asthmatic women.

Method Thirty women with and without asthma (1:1) receiving fertility treatment were studied. Asthma was defined as respiratory symptoms and bronchodilator reversibility, airway hyperresponsiveness and/or peak-flow variability. All women completed the same measures, including questionnaires, FeNO, blood samples, spirometry, bronchial provocation with methacholine, induced sputum analysis, and endometrial biopsy. The endometrial biopsy was scheduled as close to ovulation as possible.

Results Women with and without asthma were of similar age (31.6±3.3 and 33.0±4.4, respectively, ns), as well as BMI, level of lung function, sputum cell count and blood CRP. Women with asthma had more pronounced airway responsiveness, presence of allergy, and higher total IgE and b-eosinophils. Women without asthma tended to have more previous embryo transfers. The endometrial biopsy showed no significant differences between groups in plasma cells/mm2 (0.64±1.1; 1.63±3.3, ns), mast cells/mm2 (4.95±6.3; 6.72±6.7, ns) or eosinophils/mm2 (0.006±0.02; 0.002±0.01, ns). However, both groups tended to have T2 inflammatory cells in the uterus.

Conclusion Women with and without asthma receiving fertility treatment have a similar degree of T2 inflammation in the uterus.