Varicella pneumonia and pregnancy 

 "Acyclovir is not currently licensed for use in pregnancy, however, the risks from withholding treatment, particularly in the second half of pregnancy when severe complicated chicken pox are more common, probably outweigh the risks of adverse drug effects on the foetus or mother". 

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 Varicella pneumonia in adults - from European Respiratory Journal - ERJ, May 1, 2003, Vol. 21, No. 5, 886-891 

 http://erj.ersjournals.com/content/21/5/886.long