Immunoglobulin levels in maternal and neonatal sera from normal and abnormal pregnancies.

IgG, IgM and albumin levels in sera from neonates with open neural tube defects (NTD), other congenital malformations, and matched controls were measured, as were levels in sera from their mothers. Neonates with NTD had significantly lower serum IgG levels than 22 control neonatal sera. On the other hand, the mothers of these neonates with NTD had elevated serum IgG levels resulting in a striking imbalance in the mother/neonate IgG ratio. In contrast to IgG, IgM levels in maternal and neonatal sera from the NTD group were within normal values. The maternal albumin levels were however significantly increased reflecting hemoconcentration. In sera from 3 neonates born with other congenital malformations (hydrocephaly, caudal appendage and sacral tumor) the only significant changes were higher IgM levels and lower mother/neonate IgM ratios. These results are discussed in the context of materno-fetal immune responses, placental transfer of plasma proteins and the possible involvement of immunoglobulins in fetal malformation.