Risk of Major Congenital Malformations Associated With First‐Trimester Exposure to Topical Antifungal Medications: A Large Claims Database Study

Purpose Vulvovaginal candidiasis is highly prevalent among pregnant women, and its treatment is crucial. However, there is a lack of evidence regarding the risks on fetal outcomes associated with the use of antifungal medications during the first trimester of pregnancy in Japan. This study examined the association between topical antifungal use during the first trimester of pregnancy and the risk of major congenital malformations (MCMs) in infants using a Japanese database. Methods We conducted a cohort study using a pregnancy cohort nested in the JMDC Claims Database from Japan. This dataset included 12 472 women who gave birth between 2010 and 2019 and were diagnosed with vulvovaginal candidiasis. Among the antifungal medications frequently dispensed or prescribed during the first trimester of pregnancy in this cohort, miconazole, oxiconazole, and isoconazole were assessed for the risk of MCMs, using clotrimazole, an antifungal medication with established safety during pregnancy, as a reference. Results Among 12 472 women, the overall prevalence of MCMs was 5.8% ( n = 249) in women exposed to topical antifungals, while unexposed were 6.2% ( n = 508). Using propensity score overlap weight (wOR), no increased risk of MCMs in infants was observed in pregnancies exposed to oxiconazole, isoconazole, and miconazole compared to clotrimazole (overlap weighted odds ratio [95% confidence interval]: 0.875 [0.599–1.277], 1.001 [0.611–1.640], and 0.887 [0.497–1.581], respectively). Conclusion There was no significant association between topical antifungal use during the first trimester of pregnancy and the risk of MCMs in infants in Japan.