Pregnant women are considered to be a population vulnerable to influenza and COVID-19 infections, and the latest guidelines consistently recommend that they receive influenza and COVID-19 vaccinations. A cross-sectional questionnaire-based study was conducted among pregnant women in Poland to determine which factors have the greatest impact on their decision to vaccinate against influenza and COVID-19. A total of 515 pregnant women participated in the study. Among them, 38.4% (n = 198) demonstrated a positive attitude toward influenza vaccination, and 64.3% (n = 331) demonstrated a positive attitude toward COVID-19 vaccination. Logistic regression analysis revealed that the strongest influence on positive attitudes toward COVID-19 vaccination is having it recommended by an obstetrician-gynecologist (OR = 2.439, = 0.025). The obstetrician-gynecologist's recommendation to vaccinate against influenza also significantly influences the decision to vaccinate (OR = 5.323). The study results also show a strong correlation between the obstetrician-gynecologist as a source of information on influenza and vaccination and participants' positive attitudes toward vaccination (OR = 4.163). Obstetricians have a significant influence on pregnant women's decisions regarding vaccinations. Further recommendations to vaccinate and awareness-raising among obstetricians may be needed to increase the vaccination rate of pregnant women in Poland.