The type of immunoglobulin present in the foetus is

Immunoglobulin G (IgG) is the only isotype that acrosses the human placenta to the foetus. It begins around 20 weeks of gestation period. The maternal IgG crosses into the fetal circulation by means of a special placental transport receptor, the neonatal Fc receptor (FcRn) which helps in the transcytosis of IgG across epithelial cells. In humans, the maternal antibodies active over a period of 6–12 months in foetus.