Chickenpox in a newborn, particularly within the first 4 weeks of life (a condition called "neonatal varicella"), is considered a medical emergency and can be life-threatening. Their underdeveloped immune system cannot contain the virus, leading to high risks of severe complications like pneumonia, hepatitis, and inflammation of the brain (encephalitis).
The primary protection a newborn has comes from its mother. If the mother is immune to chickenpox (from having had it before or being vaccinated), she passes protective antibodies to her baby through the placenta before birth. This passive immunity offers the baby some protection, but it is temporary and typically wanes over the first 3 to 6 months of life.
To protect the infant, new parents must be vigilant. Anyone who is sick or has been recently exposed to chickenpox should not visit. All caregivers and visitors should wash their hands thoroughly before holding the baby. The most crucial step is for the pregnant mother to confirm her immunity with her doctor now. If she is not immune, she can be vaccinated immediately after giving birth to protect herself and, through her breast milk and reduced risk of exposure, her newborn in the future.