To better understand the role of posttraumatic stress disorder (PTSD) in postpartum health, this study investigates the relationship of PTSD and associated perinatal behavioral risk factors in a sample of Caucasian, Asian, and Pacific Islander women. As part of a larger longitudinal study, 54 women (18-35 years of age) were interviewed at their postpartum clinic visit for PTSD, anxiety, depression, and alcohol and substance use. PTSD and subclinical PTSD during the postpartum period were associated with behavioral health risks, with PTSD at the onset of pregnancy being a predictor of postpartum PTSD by a factor of three. Women with PTSD and subclinical PTSD were more likely to also experience stress (73%), anxiety (64%), and depression (73%) during the postpartum period compared to those without PTSD. No significant differences were found by ethnicity for postpartum PTSD, depression, or anxiety. Regardless of ethnicity or PTSD status, one in four women in the sample had a probable mental health disorder or risk behavior of some type during the postpartum period. Given the rates of associated mental health risks with PTSD, these findings suggest further research examining the fluctuations of PTSD symptomatology throughout each pregnancy trimester to determine its role as a potential mediator during the perinatal period. Further research is also needed to elucidate the role of ethnic or cultural differences in trauma and PTSD and perinatal health.