The Risk of Adverse Pregnancy Outcome After First Trimester Exposure to H1 Antihistamines: A Systematic Review and Meta-Analysis.

H1 antihistamines are used for the treatment of nausea and vomiting during pregnancy as well as the symptomatic relief of asthma, urticaria, allergy, and the common cold. Although they are overall felt to be safe during pregnancy, recently several studies have challenged this assumption, as millions of women are exposed to them in the first trimester.