Introduction

Atopic eruption of pregnancy (AEP) is the commonest dermatosis of pregnancy, accounting for half of all dermatoses in this patient group. It is a benign condition that is treated symptomatically with topical creams and emollients. Incidence is higher amongst women with a past medical or family history of atopy, and the pathogenetic mechanisms seem to relate to pregnancy-related immune changes and reduced cytokine production.

Epidemiology

AEP is known to be the most common dermatosis of pregnancy, with an incidence of 1 in 300 pregnant women.
  • In a multi-centre study examining 596 dermatoses of pregnancy, 49.7% were AEP.
  • Approximately 20% of patients with AEP have pre-existing atopic skin disease that flares into AEP during pregnancy, whilst the remainder present for the first time.
  • It can recur in subsequent pregnancies, but it is unclear if consecutive presentations are of differing severity.

Pathophysiology

AEP is thought to be related to pregnancy-related immune changes.

  • Incidence is higher amongst women with a family or personal history of atopic disease, suggesting an immune-mediated reaction.
  • Reduced production of Th1 cytokines (interleukin-2, -12, interferon gamma), in concert with elevated secretion of Th2 cytokines (IL-4, IL-10) have been proposed as causal mechanisms.
  • There are no hallmark histological findings, and immunofluorescence is negative.

Clinical features

AEP tend to affect early pregnancy, with symptoms presenting in the first or second trimester in 75% of cases.

  • Patients will present with symptoms of pruritis and discomfort in the areas affected
  • On general examination, the eruption may be found to affect all parts of the body, including the face, hands, soles of the feet
  • There is a tendency for flexural areas to be more affected however
  • On inspection, there may be:
    • Eczematous features (48%) - erythematous areas interspersed with other dry, scaly, excoriated areas
    • Papules, which may be grouped or widespread
    • Prurigo lesions (31%) - small, raised, hard nodular lesions
    • Vital signs should be normal, and with no fever

Investigations

AEP is a clinical diagnosis, and no testing is required. However, it may be necessary in some cases to ensure that other diagnoses have been ruled out.

Blood tests
Clinically mild AEP will likely be managed solely in primary care and no blood tests are necessary. However, if symptoms are widespread or very pronounced, performing blood tests may be prudent to rule out other causes.
  • Full blood count and CRP
    • Useful to rule out superimposed infection
    • AEP should not be accompanied by an elevation in infection markers
  • Liver function tests and bile acids
    • To rule out intrahepatic cholestasis of pregnancy.
    • LFTs and bile acids normal in AEP

Differential diagnosis

Other dermatoses of pregnancy are import to exclude, as although much rarer they require more urgent management.

  • Polymorphic eruption of pregnancy
    • The second most common pregnancy-related skin condition and also benign and self-limiting.
    • Presents later that AEP, commonly in the third trimester
    • Typical features include pruritic, erythematous papules found principally on the abdomen and with periumbilical sparing.

  • Intrahepatic cholestasis of pregnancy
    • A potentially serious condition associated with increased risk of stillbirth and premature labour
    • Presents first with pruritis, and skin lesions follow afterwards
    • Blood tests show raised bile acids, and possibly deranged liver function tests in contrast to AEP where blood tests should all be normal

  • Pemphigoid gestationis
    • Otherwise known as pregnancy-related bullous pemphigoid
    • Much rarer than the other dermatoses of pregnancy
    • Urticarial plaques and papules typically develop around the umbilicus, which form to develop into bullae which then spread to other parts of the body. AEP tends to develop around flexural areas, however, and bullae are not a feature.
    • An auto-immune condition, diagnosed by direct immunofluorescence of perilesional skin, and managed with topical and/or oral corticosteroids

Management

Treatment of atopic eruption of pregnancy is symptomatic, and management is for the most part within primary care.

  • Oral anti-histamines can help relieve pruritis
  • Topical therapies include emollients, 1% menthol in aqueous cream and steroid cream
  • Oatmeal baths, sunlight, and wearing light airy clothes may also help alleviate symptoms
  • Patients should be reassured that symptoms resolve spontaneously following delivery of the baby.

A referral to a tertiary dermatology or obstetric centre may be made in rare cases with very extreme, widespread, or persistent symptoms for investigation to rule out serious differentials.