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Pemphigoid Gestationis (PG)

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Also known as… Herpes Gestationis

Pemphigoid gestationis (PG) is a relatively rare pregnancy dermatosis characterised by blisters. The condition develops in the 2nd or 3rd trimester of pregnancy and may worsen around the time of delivery after which it gradually resolves. Closer monitoring of the pregnancy is often recommended.

Pemphigoid gestationis is an autoimmune condition. The mother’s immune system mistakenly forms anti-skin antibodies which destroy molecules in the zone between her skin’s epidermis (first layer of the skin) and dermis (second layer of the skin) and create a blister. It is more common in donor egg pregnancies.

Although this condition was previously called herpes gestationis, it is not caused by the herpes virus and is not contagious.

Pemphigoid gestationis may start at any stage of the pregnancy (average onset around 28 weeks) and may initially look like hives. Red bumps form on the abdomen, often first seen around the belly button (umbilicus). These areas usually develop into tense blisters of various sizes. The blisters typically cluster into groups. The rash can become widespread but the mucosa such as mouth and vagina are not usually affected. Pemphigoid gestationis is very itchy.

Women affected by pemphigoid gestationis are more likely to have preterm labour and small-for-date babies.

Approximately 5% of newborns have skin blisters caused by the transfer of the anti-skin antibodies from mother to baby. These blisters heal in weeks to months without any specific treatment as the antibodies are broken down within the baby. Pre-eclampsia is more common.

A skin biopsy shows blistering at the junction of the dermis and epidermis. Special testing of skin samples (by a technique called direct immunofluorescence) confirms the antibody deposition. Blood tests may detect the circulating auto-antibodies.

Steroid creams may be used in mild cases of pemphigoid gestationis.

Most women need oral medications to control blistering. An oral steroid (prednisolone) is commonly used until after delivery. Other immunosuppressant options include azathioprine and cyclosporin but safety during pregnancy and breastfeeding need careful consideration. Involvement of a paediatrician may be required due to the risk of babies having low birth weight or skin blistering.

If the pemphigoid gestationis persists for a long time after delivery, there may be small retained placenta that could be driving the immune response.

Pemphigoid gestationis often gets worse around the time of delivery and may take months to clear. The condition usually recurs in subsequent pregnancies and may also recur around the time of menstrual periods or with commencement of the oral contraceptive pill.

Links

www.eadv.org/patient-corner/leaflets/eadv-leaflets/pemphigoid-herpes-gestationis-pg/

www.emedicine.medscape.com/article-overview

This information has been written by Dr Genevieve Sadler

Last updated: April 2023

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