Chickenpox exposure in pregnancy Flashcards
Chickenpox exposure in pregnancy
Chickenpox is caused by primary infection with varicella-zoster virus.
Shingles is caused by the reactivation of dormant virus in dorsal root ganglion.
In pregnancy, there is a risk to both the mother and also the fetus, a syndrome now termed fetal varicella syndrome
Risks to the mother
-5 times greater risk of pneumonitis
Fetal varicella syndrome (FVS)
-FVS following maternal varicella exposure is around
–1% if occurs before 20 weeks gestation
–small number occurring between 20-28 weeks gestation and
–none following 28 weeks
features of FVS include
–skin scarring,
–eye defects (microphthalmia),
–limb hypoplasia,
–microcephaly and
–learning disabilities
Other risks to the fetus
shingles in infancy: 1-2% risk if maternal exposure in the second or third trimester
severe neonatal varicella: if the mother develops rash between 5 days before and 2 days after birth there is a risk of neonatal varicella, which may be fatal to the newborn child in around 20% of cases
Management of chickenpox exposure in pregnancy, i.e. post-exposure prophylaxis (PEP)
-urgently checked for varicella antibodies - doubt about the mother previously having chickenpox maternal blood should be
-historically, exposure has been managed through the timely administration of varicella zoster immunoglobulin (VZIG). However, the guidance has changed due to a national/international VZIG shortage. This was initially a short-term deviation from practice in 2022 but has now become baked into longer-term guidance
-oral aciclovir (or valaciclovir) is now the first choice of PEP for pregnant women at any stage of pregnancy
-antivirals should be given at day 7 to day 14 after exposure, not immediately
why wait until days 7-14? From the PHE guidelines: ‘In a study evaluating the comparative effectiveness of 7 days course of aciclovir given either immediately after exposure or starting at day 7 after exposure to healthy children, the incidence and severity of varicella infection was significantly higher in those given aciclovir immediately (10/13 (77%) who received aciclovir immediately developed clinical varicella compared with 3/14 (21%) who started aciclovir at day 7)’
Management of chickenpox in pregnancy
if a pregnant woman develops chickenpox in pregnancy then specialist advice should be sought
there is an increased risk of serious chickenpox infection (i.e. maternal risk) and fetal varicella risk (i.e. fetal risk) balanced against theoretical concerns about the safety of aciclovir in pregnancy
consensus guidelines (Health Protection Authority and RCOG) suggest oral aciclovir should be given if the pregnant women is ≥ 20 weeks and she presents within 24 hours of onset of the rash
if the woman is < 20 weeks the aciclovir should be ‘considered with caution’
