Maternal antibodies are transported across the placenta mainly during which part of pregnancy?

1. The commonest form of passive immunity is what an infant receives from its mother. 2. IgG crosses the placenta primarily during the last 1 to 2 months of pregnancy. 3. A full-term infant therefore carries the same types of antibody as the mother and is protected for the first few months of life. 4. The timing explains why a preterm infant, delivered before that transfer is complete, starts with less maternal antibody. 5. Protection is better against some diseases, such as measles, rubella and tetanus, than against polio and pertussis. _Source: CDC Epidemiology and Prevention of Vaccine-Preventable Diseases (Pink Book), section Passive Immunity_