Amniotic fluid, maternal and cord serum IgD determinations were performed in 30 healthy pregnant women during labor. Immunoglobulin D was determined by simple radial immunodiffusion by using low concentration immunoplates. Maternal serum IgD mean level amounted to 4.39 mg/100 ml, while in fetal serum and amniotic fluid no immunoglobulin D was detected in any of the cases presented. The absence of IgD in the amniotic fluid supports the view of a special mechanism which exerts selective inhibition of its passage into the amniotic cavity
