Talk with doctor
A mom who has shingles
and also has a newborn should not have a problem, but she should double check with the pediatrician.
The reason is that the mom had already gotten chicken pox in the past (otherwise she would not be able to get shingles). The mom's chicken pox antibodies should be inside the newborn (unless the baby was too premature) and protecting the newborn from shingles or chicken pox.