Placental transfer of maternal rubella antibodies to full-term and preterm infants.

Premature infants are vulnerable to infections, partly because of the low transplacental transfer of maternal antibodies. The present study investigated the placental transfer of maternal rubella-specific antibodies to full-term and preterm infants. The study group consisted of 133 healthy, native Israeli mothers and their 159 newborns. Of these, 69 were full-term infants (gestational age > 37 weeks) of 69 mothers, and 90 were preterm infants (gestational age < 35 weeks) of 64 mothers. Antibody titers against rubella were measured in maternal and umbilical cord blood samples by hemagglutination inhibition and microneutralization techniques. There was no significant difference in the level of protection and in geometrical mean titers by hemagglutination between the full-term and preterm groups. Conversely, significant differences in geometric mean titers of neutralizing antibodies were found between full-term and preterm infants, e.g., 65.9 and 39.8, respectively (P < 0.001). Very low birth weight preterm infants are at greater risk of rubella infection during the first year of life, due to the diminished transfer of neutralizing maternal antibodies. Therefore, earlier vaccination of this group may be beneficial.