Posttraumatic stress disorder (PTSD) is pervasive among women of childbearing age. The cascade of behavioral health and neuroendocrine changes commonly associated with PTSD may adversely affect perinatal health. The authors examined the relationship between PTSD and perinatal health in a sample of 101 women seeking prenatal care on the island of Oahu, Hawaii. Trauma, PTSD, and psychological and behavioral health were assessed during prenatal care. Pregnancy health, labor and delivery information, and birth outcomes were abstracted from medical records post-partum. Findings suggest that women with PTSD entering pregnancy are at increased risk for engaging in high-risk health behaviors, such as smoking, alcohol consumption, substance use, poor prenatal care, and excessive weight gain. Authors discuss clinical and research implications.