In the UK, chickenpox (primary varicella virus infection) is usually a mild, self-limiting disease of childhood. It is more severe in adults. For example, of every 100,000 people who contract chickenpox, around 4-9 die from it, of whom 81-85% are adults. Chickenpox infection in pregnant women can lead to a severe maternal illness and it appears five times more likely to be fatal than in non-pregnant women. Although most women who have chickenpox in pregnancy give birth to healthy children, in other cases, the baby is harmed by in-utero infection or severe varicella of the newborn. Here we review the risks and key aspects of diagnosis and further management of varicella infection in pregnancy and the neonatal period.