Safety of Venom Immunotherapy in Pregnancy: A Multicentre Study

Venom immunotherapy (VIT) is a crucial therapy in Hymenoptera Venom Allergy (HVA), but limited data exist on VIT during pregnancy. However, untreated HVA poses a dangerous risk of severe anaphylaxis for both the pregnant woman and her foetus. This study aimed to evaluate the safety and efficacy of maintenance VIT during pregnancy, focusing on spontaneous abortion, preterm birth and adverse events (AEs), compared with rates expected in the general population.

We conducted a prospective, longitudinal, multicentre study across 14 Italian allergy centres, including women who became pregnant while receiving maintenance VIT. Safety outcomes were frequencies of spontaneous abortion, preterm birth and VIT-related AEs during pregnancy. Efficacy was assessed by reactions to field stings. Regression analyses evaluated factors associated with safety and efficacy.

Sixty-eight women with 86 pregnancies were included. Spontaneous abortion occurred in 11 pregnancies (12.8%) and preterm birth in 6 cases (8.1%). These figures were comparable to those in the general population. Older maternal age and previous abortions were associated with abortion in the unadjusted analysis, but no VIT-related characteristics were raised as risk factors. Only one mild, self-limiting AE to VIT occurred during pregnancy. Five women experienced field stings and only one large local reaction was reported, with no subsequent adverse pregnancy outcomes.

Continuation of well-tolerated maintenance VIT during pregnancy was safe and effective, with no increased risk of abortion, preterm birth, or significant AEs and with preserved protection against sting reactions. These findings support continuing maintenance VIT during pregnancy.