Counselling of mother who has developed chickenpox in pregnancy

If woman has chickenpox in pregnancy:

• see management of chickenpox in pregnancy (linked item) regarding medical management issues
• if uncomplicated chickenpox then should be advised to report promptly any symptoms that suggest complications (e.g. chest symptoms, haemorrhagic rash, bleeding)
• should avoid contact with anyone potentially at risk of developing severe chickenpox, particularly other pregnant women or neonates
• risk of fetal varicella syndrome (this might still occur despite the administration of varicella zoster immune globulin (VZIG))
  • pregnant woman with chickenpox who has not received VZIG:
    • the likelihood of transplacental varicella infection about 8%
    • likelihood of fetal varicella syndrome is lower - about 2.8%
  • woman should be offered referral to a specialist centre for detailed ultrasound examination at around 5 weeks after her varicella infection to look for the specific anomalies of fetal varicella syndrome
    • if ultrasound examination is suggestive of the syndrome then amniotic fluid can be tested for varicella zoster virus-DNA
      • fetal infection is excluded if such testing is negative at 18-22 weeks of pregnancy and a scan is negative after 23 weeks

Notes:

• evidence indicates that there is a small risk of fetal varicella syndrome where the mother develops chickenpox after 20 weeks of pregnancy, with the risk extending to at least week 28. Healthcare professionals caring for pregnant women must bear this in mind (2)

Reference:

1. Drug and Therapeutics Bulletin 2005; 43(9): 69-72.
2. Drug and Therapeutics Bulletin 2005; 43(12):94-5.