Prolonged Exposure Therapy to Treat Posttraumatic Stress Disorder in Pregnant Patients

The goal of this clinical trial is to learn if a treatment for adults with PTSD called prolonged exposure + incentives (PE+) works to treat pregnant patients. The main question it aims to answer is: Does PE+ decrease PTSD symptoms? All participants will receive PE+ to see if their PTSD symptoms at the end of the trial are less than at the beginning. Participants will: * Receive individual PE+ therapy for 1 hour weekly for 12 weeks. * Receive financial incentives for attending each PE+ session. * Attend assessment visits every 4 weeks for the 12 weeks of the trial. * Allow research staff to collect some information about their labor and delivery from their medical records after their babies are born.