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No Evidence of Adverse Pregnancy Outcomes in Women Treated with Allergen-specific Immunotherapy Early in Pregnancy

For Release

April 25, 2022

April Presnell, Media & Member Communications Manager  
(414) 272-6071

There was no statistically significant increased risk for congenital malformations, stillbirths, preterm births, or caesarean delivery in the study population, according to research published in an official journal of the AAAAI.

Milwaukee, WI – A new study showed no evidence that women experienced adverse events in their pregnancies if they had been treated with allergen-specific immunotherapy (AIT) three months prior to conception up to gestational week 22. The new research was published in The Journal of Allergy and Clinical Immunology: In Practice (JACI: In Practice), an official journal of the American Academy of Allergy, Asthma & Immunology (AAAAI).

AIT is the process of administering specific allergens to patients with IgE-mediated diseases to increase their tolerance and protect them from allergic reactions. It typically takes three to five years to complete treatment. While AIT helps prevent exacerbations of asthma and allergic rhinitis, which can harm both the mother and fetus, limited research has been done on the safety of AIT use during pregnancy. It is currently not recommended that women begin AIT during a pregnancy, though women who are being treated already with well-tolerated AIT may continue it during pregnancy.

Researchers in Sweden collected data from nationwide Swedish healthcare registers from 2005-2014, which includes data on nearly all births in Sweden, and identified pregnancies with at least one record of AIT in the three months prior to conception up to gestational week 22 during the study period. A total of 743 pregnancies meeting the study criteria were identified.

“Our primary aim was to examine congenital malformations, though we did also study a variety of other adverse pregnancy outcomes,” said Niki Mitselou, MD, corresponding author of the study. “We used logistic regression analysis to estimate odds ratios and adjusted for confounding factors such as maternal age at delivery, smoking during pregnancy and many other factors.”

Among pregnant women exposed to AIT, 4.4% experienced congenital malformation, compared to 3.9% in pregnant women without AIT, which is not statistically significant. Researchers also found no significant increased risks for other adverse pregnancy outcomes, including preterm birth, stillbirth, or caesarean delivery. Further analyses examined route of immunotherapy and found no differences between the groups, whether AIT was administered subcutaneously or sublingually.

Additionally, researchers performed a separate analysis in pregnant women who first began AIT during pregnancy and found they actually experienced a lower risk of congenital malformations and preterm births. Risk estimates for the other pregnancy outcomes did not show any other significant differences.

“While we did not find an association between adverse pregnancy outcomes and the use of AIT, more research needs to be completed on the immune response of children when the pregnant mother has been exposed to AIT,” said Dr. Mitselou. “In the meantime, this research will help physicians and pregnant women make an informed decision about if AIT is right for them during their pregnancy.”

You can learn more about immunotherapy on the American Academy of Allergy, Asthma & Immunology website,

The American Academy of Allergy, Asthma & Immunology (AAAAI) is the leading membership organization of more than 7,100 allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic and immunologic diseases. The AAAAI is the go-to resource for patients living with allergies, asthma and immune deficiency disorders. Established in 1943, the AAAAI has more than 7,100 members in the United States, Canada and 72 other countries. AAAAI’s Find an Allergist/Immunologist service is a trusted resource to help you find a specialist close to home.