Till Örebro universitet

Allergic diseases are very common in children and young adults, while there is an ongoing interest worldwide in exploring the early origins of these conditions. The perinatal period is considered crucial as it encompasses the maturation of gut microbiota and the establishment of an efficient immunoregulation. Early-life factors might be the key drivers of an altered immune response, sometimes leading to sensitization and allergic disease. Preterm birth is believed to affect the risk of immune-mediated diseases, while a delayed and altered gut microbiota composition and diversity following caesarean delivery might influence the induction of tolerance.

In the first paper, using a large population database, we found that caesarean delivery increased the risk of allergic rhinitis (AR) in offspring, while moderately preterm birth (≥32–36 weeks of gestation) was associated with a slightly elevated risk. No association was observed between post-term birth (≥42 weeks) and AR. There also seems to be a positive association between large for gestational age, low 5-minute Apgar score (<7) and AR. 

In the second paper, we used data from the BAMSE population-based birth cohort to assess the impact of gestational age at birth on future IgE sensitization. The study concluded that preterm birth (<37 weeks of gestation) was inversely associated with IgE sensitization to common food and/or inhalant allergens up to the age 24 years, while no association was found between postterm birth and IgE sensitization.

Uncontrolled asthma and allergic disease in pregnancy are associated with poor pregnancy outcome. Current guidelines recommend against the initiation of allergen-specific immunotherapy (AIT) in pregnant patients, while welltolerated ongoing AIT might be continued. In the third paper, using national health-care registers, we found no association between AIT during pregnancy and risk of congenital malformations, preterm birth, caesarean delivery, stillbirth, or other adverse pregnancy outcomes.