This study is associated with a larger parent study. Participants in this open-label study may be recruited directly for this study or through the parent study. All participants will receive 16 sessions of IPT. Sessions will last approximately 50 minutes and will focus on achieving depression symptom remission by improving interpersonal functioning. The majority of IPT sessions will be held prior to delivery; up to four sessions may be held postpartum. No medication will be provided in this study, but women who are currently taking selective serotonin uptake inhibitors (SSRIs) at the time of study entry may continue taking their medication. Participants whose symptoms do not improve with IPT will be referred to their non-study physician for further evaluation, and may begin taking SSRI medication upon physician recommendation. The effects of both IPT and medication therapy will be considered when assessing outcomes. Study visits will occur at 28, 32, and 36 weeks gestation, as well as Weeks 1, 2, and 6, and Month 6 postpartum. Measurements will include cortisol levels, which will be obtained using a saliva sample, as well as depression symptom severity, which will be assessed at each IPT session. Blood samples will be taken as part of the parent study.