Infants are born with a passive immunity that occurs when immunoglobulin antibodies cross the placenta from the maternal circulation prior to birth. Which immunoglobulin is capable of crossing the placenta?

Immunoglobulin G (IgG)

Explanation:

There are five classes of human antibodies:

IgG is the most abundant and the only one capable of crossing the placenta. IgG is present in all body fluids and protects against infections.

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.