Pemphigoid gestationis (PG) is a rare, itchy skin eruption that occurs in the second or third trimester of pregnancy. The affected area of the skin shows itchy red bumps or blisters and plaques on the abdomen and trunk, but they also may show up on other parts of the body.
PG was also known as herpes gestationis, but now, it’s understood that it has no connection to the herpes virus. The term pemphigoid was from the word “pemphigus” which refers to a blister or pustule, and gestationis, which means “of pregnancy” in Latin.
The itchy bumps that appear on the skin of a person with PG spreads around the belly button to other parts of the body such as the face, scalp, palms, and soles of the feet. When it worsens, (usually after two to four weeks) the bumps turn into larger, fluid-filled blisters called bulla. Fortunately, PG blisters shrink and go away on their own toward the end of the pregnancy. However, 75 to 80% of women with PG still experience flare-ups around the time of delivery. In very rare cases, PG can also appear in newborns.
PG is now understood to be an autoimmune disease, meaning the body’s immune system begins to attack parts of your own body. In PG, the cells of the placenta becomes under attack. This is because the placental tissue contains cells derived from the father, which are recognized as foreign by the mother’s immune system. Paternal cells are normally present in every pregnancy, but the chances of it getting attacked by the mother’s immune system in PG are rare.
However, certain molecules known as MHC II that are not normally present in the placenta have been found in women with PG. When a pregnant woman’s immune system detects these molecules, it launches an attack. MHC II-class molecules are responsible for the sticking together of the skin’s layers. When the immune system attacks them, the body reacts, causing blisters and plaque. One measure of this reaction is the presence of a protein now known as Collagen XVII (formerly known as BP180).
Pruritic urticarial papules and plaques of pregancy, also known as PUPPP, can resemble pemphigoid gestationis. This often occurs in the third trimester, which is also a common time for PG to appear. Like PG, the symptoms appear first on the abdomen as itchy red bumps or plaques.
A dermatologist can perform a skin biopsy to confirm PG. The process involves applying local anesthetic or freezing spray to a small area of the skin and cutting a sample for lab testing. Laboratory experts will further do an immunofluorescence analysis that can confirm PG. Aside from skin biopsy, doctors may also take blood samples to determine the levels of pemphigoid antigen Collagen XVII/BP180 in the blood to assess the disease activity.
Mild symptoms may be relieved using topical corticosteroids for the itch, also to prevent the formation of blisters. Over-the-counter antihistamines can also help. However, it is important to talk to your doctor before taking any medications, even over-the-counter products during pregnancy.
Relieving the itch and discomfort caused by a mild case of PG is easier with some home remedies including:
- ice or cold compresses
- staying in a cool or air-conditioned room
- bathing in Epsom salt or oatmeal preparations
- wearing hypoallergenic or 100% pure organic clothing
For severe cases, doctors may prescribe oral corticosteroids, as these drugs act by reducing the activity of the immune system. Because PG occurs during pregnancy, the doctor will take into account the effects on both the mother and the baby and keep the dosage and duration of treatment to a minimum.
A 2009 study published in the British Journal of Dermatology found that outbreaks of PG blisters in the first and second trimester may lead to adverse pregnancy outcomes. This was seen in women with early-onset (first or second trimester) of PG included preterm birth, low birth weight, and small for gestational age. The authors recommend that PG that occurs in the first or second trimester should be treated as a high-risk pregnancy with more careful monitoring and supervision.