Purpose: This study investigated the effects of prenatal education characteristics, pandemic-related pregnancy stress, and health behaviors during pregnancy on prenatal depression in pregnant women during the coronavirus disease 2019 (COVID-19) pandemic.Methods: The participants were 180 pregnant Korean women, recruited from internet communities for pregnancy preparation, childbirth, and childcare, from July 5 to 15, 2022. The collected data were analyzed using the t-test, analysis of variance, the Mann-Whitney U-test, the Kruskal-Wallis test, and multiple regression analysis.Results: The scores for pandemic-related pregnancy stress (24.50±6.37) and health behaviors during pregnancy (67.07±9.20) were high. Nearly half of the participants (n=89, 49.4%) presented with prenatal depression, with scores of 10 or greater. Prenatal depression had a positive correlation with gestational age (r=.18, p=.019) and pandemic-related pregnancy stress (r=.27, p<.001), and a negative correlation with health behaviors during pregnancy (r=–.42, p<.001). The factors associated with prenatal depression were pandemic-related pregnancy stress (t=4.70, p<.001), marital satisfaction (dissatisfied) (t=3.66, p<.001), pregnancy healthcare practice behaviors (t=–3.31, p=.001), family type (weekend couple) (t=2.84, p=.005), and gestational age (t=2.32, p=.022). The explanatory power of these variables was 38.2%.Conclusion: Since participants had a high level of prenatal depression during the pandemic, and infectious diseases such as COVID-19 may recur, strategies should be developed to improve pregnant women’s mental health with consideration of the unique variables that are relevant in a pandemic. It is also necessary to develop efficient online prenatal education programs that can be implemented even in special circumstances such as social distancing, and to evaluate their effectiveness.