Autoimmune progesterone dermatitis following vaginal progesterone exposure in pregnancy

In the non-pregnant state, exogenous as well as endogenous fluctuations of progesterone have been demonstrated to cause a rare delayed hypersensitivity reaction known as autoimmune progesterone dermatitis. We describe the case of a 20-year-old woman in her second pregnancy who presented to our delivery unit at 31 weeks and 3 days gestation for a cutaneous breakout with pruritic pustules, blisters, and crusts across her chest back and extremities 23 days after the initiation of vaginal progesterone. After suspension of the vaginal progesterone, the patient's cutaneous lesions resolved. Differential diagnosis and management strategies are discussed. With the increased use of progesterone during pregnancy, complications arising from their use will rise. Clinicians should be aware of their potential adverse effects and consider autoimmune progesterone dermatitis in the differential diagnosis of patients presenting with pruritic lesion in pregnancy.