Herpes gestationis (pemphigoid gestationis) is a rare, generalised blistering rash that occurs in pregnancy between the fourth and seventh months, and sometimes after delivery. It occurs in less than one in ten thousand pregnancies, and is an autoimmune reaction that may be aggravated by oestrogen. It is not an infection, and not related to genital herpes.
Patients develop extremely itchy, fluid filled, scattered small lumps on the body, particularly the belly, sides of the trunk, palms and soles. These may enlarge to form large fluid filled blisters, before bursting and forming crusts.
A biopsy of one spot is normally necessary before the diagnosis can be confirmed.
Prednisone tablets, starting at a high dose and gradually reducing are the usual treatment.
The prognosis is good and the condition usually does not affect the baby, but it tends to recur in subsequent pregnancies.