What is a unique feature of IgG antibodies?

IgG antibodies are unique in that they are the only type of antibody that can cross the placenta from the mother to the fetus. This property is significant as it allows for the passive transfer of immunity, meaning that the fetus receives some level of immune protection from the mother against infections during pregnancy. This transfer of IgG antibodies can help safeguard the newborn during the early months of life until its own immune system is capable of producing antibodies in response to pathogens.

This feature highlights the importance of IgG in maternal-fetal health and immune system development, establishing a critical link between maternal and neonatal immunity. Other antibody classes, like IgM, do not possess this ability, making IgG distinct in the context of immunity and prenatal health.