Dermatoses of Pregnancy

The single most useful discriminator between the common pregnancy dermatoses is whether the umbilicus is involved or spared. Pemphigoid gestationis begins at the umbilicus; polymorphic eruption of pregnancy characteristically spares it.

Polymorphic Eruption of Pregnancy (PEP / PUPPP)

• Timing: third trimester
• Incidence: approximately 1 in 160 pregnancies — the commonest
• Distribution: abdominal striae, thighs, extensor surfaces of the limbs
• Umbilicus: spared
• Appearance: itchy erythematous papules
• Systemic illness: none
• Course: self-limiting
• Fetal effects: none
• Recurrence: does not recur in subsequent pregnancies

Pemphigoid Gestationis

• Timing: second or third trimester
• Incidence: rare, approximately 1 in 50,000 pregnancies
• Distribution: starts within the umbilicus, then spreads to limbs, palms and soles
• Umbilicus: not spared — this is the key distinguishing feature from PEP
• Appearance: clusters of vesicles and bullae on erythematous, urticarial papules
• Pathology: autoimmune. Skin biopsy shows C3 deposition along the basement membrane
• Associations: molar pregnancy and choriocarcinoma
• Course: often improves during the third trimester but flares 24–48 hours after delivery
• Scarring: yes
• Fetal effects: small for gestational age — monitor fetal growth. Approximately 5% of neonates develop bullous lesions. Adrenal insufficiency may follow maternal steroid therapy
• Recurrence: recurs earlier and more severely in subsequent pregnancies

Intrahepatic Cholestasis of Pregnancy

• Timing: third trimester; begin screening at 28 weeks in those at risk
• Epidemiology: more common in South American and Scandinavian populations
• Distribution of itch: palms, soles and shins
• Umbilicus: spared
• Appearance: no primary rash — excoriations only. Pruritus without a rash is the hallmark
• Systemic features: raised bile acids and transaminases; jaundice if severe
• Course: resolves after delivery. Repeat bile acids and liver function tests at 10 days postpartum to confirm resolution
• Fetal and maternal effects: preterm birth, intrapartum fetal distress, stillbirth (sudden, thought to be a cardiac arrhythmic or hypoxic mechanism rather than progressive placental failure), and postpartum haemorrhage
• Recurrence: 75–90% in subsequent pregnancies

Impetigo Herpetiformis

• Timing: third trimester; acute and rare. Regarded as a pustular psoriasis of pregnancy
• Distribution: intertriginous areas — groin, underarms — and mucous membranes of mouth and genitals
• Umbilicus: spared
• Appearance: small pus-filled blisters, irregular or clustered, which scab and dry before new blisters appear at the edge of the dried rash. Hair loss may occur
• Systemic illness: yes, and severe — chills, vomiting, diarrhoea, joint pains. Maternal death is described
• Course: resolves after delivery
• Fetal effects: stillbirth
• Recurrence: yes

Prurigo of Pregnancy

• Timing: second trimester
• Incidence: approximately 1 in 300 pregnancies
• Distribution: extensor surfaces of the upper limbs, abdomen and thighs
• Umbilicus: spared
• Appearance: itchy papular eruptions
• Systemic illness: none
• Course: may persist up to 12 weeks postpartum
• Fetal effects: none
• Recurrence: variable

Pruritic Folliculitis of Pregnancy

• Timing: second trimester
• Incidence: approximately 1 in 3,000 pregnancies
• Distribution: upper trunk and back
• Umbilicus: spared
• Appearance: pruritic, erythematous follicular papules
• Systemic illness: none
• Fetal effects: none

Examination Discriminators

| Feature | Points to | |---|---| | Starts at the umbilicus | Pemphigoid gestationis | | Spares the umbilicus, in striae | Polymorphic eruption of pregnancy | | Itch with no rash, palms and soles | Intrahepatic cholestasis of pregnancy | | Pustules with systemic illness | Impetigo herpetiformis | | C3 on basement membrane | Pemphigoid gestationis | | Recurrence 75–90% | Intrahepatic cholestasis of pregnancy | | Recurs earlier and worse | Pemphigoid gestationis | | Does not recur | Polymorphic eruption of pregnancy |

References

• The Obstetrician & Gynaecologist (TOG), RCOG journal — dermatoses of pregnancy reviews
• RCOG Green-top Guideline 43, Obstetric Cholestasis

Source: The Obstetrician & Gynaecologist (TOG), RCOG journal — see references below

Clinically reviewed by NHS obstetricians and gynaecologists

MRCOG AI is an independent educational tool. It is not affiliated with, endorsed by, or connected to the Royal College of Obstetricians and Gynaecologists (RCOG).