Purpose: The purpose of this study was to identify the influences of oral health behaviors, depression, and stress on periodontal disease in pregnant women. Methods: The participants in this study were 129 pregnant women. Data were collected using questionnaires which included individual characteristics, oral health care behaviors, the Center for Epidemiological Studies-Depression scale (CES-D), a global measure of perceived stress, and pregnancy stress. A dentist measured periodontal probing depth and classified stages of periodontal disease according to the Community Periodontal Index (CPI). Data were analyzed using descriptive statistics, Pearson correlation, and multiple regression. Results: Periodontal disease had significant correlations with oral health care behaviors (r=-.56, p qqqlt;.001), perceived stress (r=.44 p qqqlt;.001), pregnancy stress (r=.37 p qqqlt;.001), diet (r=-.33, p qqqlt;.001) and depression (r=.18 p =.046). Factors influencing periodontal disease for these pregnant women were being in the 2nd (β=.27, p qqqlt;.001) or 3rd trimester (β=.45, p qqqlt;.001), having a pregnancy induced disease (β=.20, p =.002), performing higher oral health behaviors (β=-.30, p qqqlt;.001), and having higher perceived stress (β=.17, p =.028). The explanation power of this regression model was 61.6% (F=15.52, p qqqlt;.001). Conclusion: The findings of this study indicated that periodic assessment of periodontal disease is essential for pregnant women who are in 2nd or 3rd trimester and have pregnancy induced diseases. Enhancing oral health care behaviors and reducing perceived stress are indicated as effective strategies to reduce periodontal disease in pregnant women.