Inclusion Criteria:

• 1. Female, 18-45 years of age
• 2. Chronic (at least one month post-trauma) DSM-5 PTSD symptoms
• 3. CAPS-5 Past Month score ≥ 26
• 4. Criterion A traumatic event
• 5. Stable medications for 3 or more months by the time of study entrance (with the exception of benzodiazepines)
• 6. Women on oral contraceptives, specifically those using monophasic or biphasic of first, second, third or fourth generation with up to 35mcg of ethinyl estradiol; OR using etonogestrel / ethinyl estradiol 0.120mg/0.015mg per day vaginal ring (NuvaRing) birth control; OR using the norelgestromin / ethinyl estradiol 0.150mg/0.035mg per day transdermal patch birth control.
• 7. Willing and able to provide informed consent

Exclusion Criteria:

• 1. Diagnosis of bipolar I disorder with a past year manic episode
• 2. Diagnosis of a psychotic disorder or psychotic symptoms that would interfere with the ability to focus on posttraumatic stress disorder (PTSD) in clinic, as determined by clinical judgment.
• 3. Diagnosis of moderate or severe substance use disorder that would interfere with the ability to focus on posttraumatic stress disorder (PTSD) in clinic, as determined by clinical judgment.
• 4. Cognitive impairment that would interfere with the ability to focus on posttraumatic stress disorder (PTSD) in clinic, as determined by clinical judgment.
• 5. History of neurological disease (that involves the brain), seizure, or significant head trauma (i.e., extended loss of consciousness, neurological sequelae, or known structural brain lesion).
• 6. Suicidal ideation with imminent risk that warrants a higher level of care.
• 7. Concurrent trauma focused psychotherapy
• 8. Pregnancy (to be ruled out by urine ß-HCG).
• 9. Metallic implants or devices contraindicating magnetic resonance imaging by interfering with patient safety or fMRI data collection. Cases will be cleared by the Principal Investigator and Center for Brain Imaging
• 10. History of breast cancer or hormone-responsive cancer.
• 11. Use of benzodiazepines
• 12. Self-injurious behavior that involves suicidal intent, requires medical attention, or occurs daily.