Complications of chickenpox in pregnancy

These are mostly as a result of infection of the foetus which may result in:

• the varicella syndrome when infection occurs early in pregnancy (1)
  • risk of fetal varicella syndrome
    • risk of the syndrome in children exposed to chickenpox in utero is around 0.5% if maternal chickenpox develops at 2-12 weeks of pregnancy
    • 1.4% if it develops at 12-28 weeks
    • 0% if it develops from 28 weeks onwards
    • overall risk in the first 20 weeks of pregnancy is 0.91%
• neonatal chickenpox can be severe when the maternal rash appears between five days before delivery and two days after delivery. Mortality may be as high as 30% without active treatment (2)

In the mother, smokers in the second or third trimester are at a particularly high risk of pneumonitis.

Notes:

• there is no evidence that uncomplicated chickenpox in the mother significantly increases the likelihood of spontaneous abortion during the first 20 weeks of pregnancy (3.0% in one study) or intrauterine death after the 20th week (0.7%) (3)

Reference:

• (1) Drug and Therapeutics Bulletin 2005; 43(12): 94-95.
• (2) Tunbridge AJ et al. Chickenpox in adults - Clinical management. Journal of Infection 2008;57:95e102
• (3) The Green Book. Immunisation against infectious disease. HMSO. London 1996.
• (4) Drug and Therapeutics Bulletin 2005; 43(9):69-72.