Allergen-specific immunotherapy appears safe during pregnancy

Women who received allergen-specific immunotherapy before or during pregnancy experienced no increased risk for adverse pregnancy outcomes, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.

“Our primary aim was to examine congenital malformations, though we did also study a variety of other pregnancy outcomes,” Niki Mitselou, MD, doctoral student in the department of pediatrics at Örebro University Hospital in Sweden, said in a press release.

The researchers examined data from 924,790 singleton pregnancies in Sweden between 2005 and 2014. These pregnancies included 743 where mothers had been exposed to allergic-specific immunotherapy (AIT) between 3 months before conception and gestational week 22.

“We used logic regression analysis to estimate odds ratios and adjusted for confounding factors such as maternal age at delivery, smoking during pregnancy and many other factors,” Mitselou said.

Mothers who received AIT had a median maternal age at delivery of 31 years (interquartile range [IQR], 6 years), compared with 30 years (IQR, 7 years) for those who did not undergo AIT.

The researchers found 4.4% of pregnancies exposed to AIT had congenital malformations compared with 3.9% of pregnancies not exposed to AIT, a difference that was considered nonsignificant (adjusted OR = 0.9; 95% CI, 0.63-1.27).

Also, the researchers found no associations between AIT and preterm birth (OR = 0.98; 95% CI, 0.71-1.35), stillbirth (OR = 0.79; 95% CI, 0.26-2.47), cesarean delivery (OR = 0.91; 95% CI, 0.76-1.09), elective delivery (OR = 0.98; 95% CI, 0.77-1.27) or emergency delivery (OR = 0.86; 95% CI, 0.68-1.09).

When evaluating the risk for congenital malformations stratified by type of AIT, subcutaneous immunotherapy (n = 563) had an OR of 0.8 (95% CI, 0.54-1.17) and sublingual immunotherapy (n = 204) had an OR of 1.38 (95% CI, 0.61-3.1), similar to adverse outcome results for the full AIT cohort.

The researchers also found similar results when they restricted the cohort to mothers with asthma or pulmonary disease, nulliparous mothers or births between 2012 and 2014.

Further, the 165 mothers who began AIT during pregnancy saw decreased risk for congenital malformations (OR = 0.53; 95% CI, 0.29-0.94), preterm birth (OR = 0.53; 95% CI, 0.31-0.91) and low Apgar score (less than 7) at 5 minutes (OR = 0.28; 95% CI, 0.13-0.6).

However, the researchers hypothesized that these inverse associations may be due to clinicians initiating AIT in particularly healthy pregnant women who do not have other risk factors or comorbidities.

“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,” Mitselou said. “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.”

Reference:

• No evidence of adverse pregnancy outcomes in women treated with allergen-specific immunotherapy early in pregnancy. https://www.aaaai.org/About/News/News/pregnancy-outcomes. Posted April 25, 2022. Accessed April 27, 2022.