This study examined maternal pregnancy wantedness and perceptions of paternal wantedness, and their associations with maternal perinatal mental health symptoms and relationship dynamics. Low-income, ethnically-diverse pregnant women (N = 101, Mage = 29.10years, SDage = 6.56, rangeage = 18-44; 37% Latina, 22% African-American, 20% White, 21% biracial/multiracial/other) completed semi-structured interviews of pregnancy wantedness coded by trained raters, and standardized instruments of depression and PTSD symptoms during pregnancy and at 3-4-months postpartum. While maternal pregnancy wantedness (rated from 0-Predominately Ambivalent, 1-Mixed, and 2-Predominately Positive) showed no significant associations, a couple-level scale that combined maternal wantedness and her perceptions of paternal wantedness (Equally Positive Wantedness, Mom Wants More, Dad Wants More and Equally Ambivalent) showed several significant associations. Compared to women in the Equally Positive group, women in the Mom Wants More group had significantly higher prenatal and postnatal depression symptoms, prenatal PTSD symptoms, and prenatal and postnatal relationship conflict; and lower prenatal and postnatal relationship support. Women in the Mom Wants More group also had significantly higher prenatal and postnatal depression symptoms and prenatal conflict; and lower prenatal support than women in the Dad Wants More group. Women who perceive themselves as wanting the pregnancy more than their baby's father are at higher risk for mental health and relationship problems than women who perceive themselves and their partners as equally ambivalent. Providers should ask women about their perceptions of partners' pregnancy wantedness to inform delivery of targeted mental health and relationship-based intervention during pregnancy.