Progesterone for Smoking Relapse Prevention Following Delivery

Inclusion Criteria: * Need to be within 3 weeks of delivery because relapse to smoking happens early after childbirth * Aged 18 to 42 years * history of smoking, with smoking and other nicotine product abstinence achieved in the final two months of pregnancy and at delivery * In good health as verified by medical history * Using acceptable birth control methods other than hormonal contraceptives that contain progestins * Have biologically confirmed abstinence from tobacco and other nicotine products at randomization Exclusion Criteria: * A history of major medical illnesses including liver diseases, suspected or known malignancy, thrombophlebitis, liver failure, or other medical conditions that the physician investigator deems will make study participation unsafe for the subject * Current or past history bipolar disorder or schizophrenia or current diagnosis of major depression, panic disorder or post-traumatic stress disorder * Dependence on and/or abuse of alcohol or other drugs of abuse in the month prior to randomization into the trial * the presence of suicidal or homicidal ideation, or significant impairment of social or occupational functioning, either at study baseline during the evaluation process, or during participation in the trial * inability to speak Spanish or English (our group is bilingual) * plans to move out of the area within 8 months after study screening since this will make follow-up difficult * Inability to understand study procedures or provide informed consent * Currently undergoing treatment with another pharmacological agent for smoking cessation * pending legal case that may result in incarceration since this would force abstinence and impede follow-up; * Pending case with child protective services that might lead removal of infant from mother's custody, as this would impede breastfeeding and infant follow-up * Unwilling to accept randomization * Subsequent pregnancy since that would be another source of progesterone * An acute general medical condition that would require imminent re-hospitalization since this would enforce abstinence (women may be randomized if they are discharged and still within the recruitment window) * Allergy to progesterone or peanuts (vehicle for micronized progesterone) * Currently undergoing treatment with ketoconazole or any other known strong CYP3A4 inhibitors