[Herpes gestationis].
On the basis of two cases of herpes gestationis, the authors review this rare dermatosis which only occurs during pregnancy. In particular, they emphasise its auto-immune origin. Indirect immunofluorescence can be used to demonstrate the so-called herpes gestationis factor (HGF), a heat stable immunoglobulin G (IgG), in the maternal and foetal blood. The maternal prognosis is good and the cutaneous lesions respond well to treatment. The foetal prognosis is also good, however the transplacental transfer of the HGF is associated with a risk of foetal death and neonatal bullous dermatosis. In terms of aetiopathogenesis, the auto-immune HGF factor suggests a hypothesis of sensitisation to placental, foetal and/or paternal antigens under the influence of hormonal factors.