Placental transfer of rubella-specific IgG in fullterm and preterm newborns

Objectives: This study was undertaken to investigate placental transfer of anti-rubella IgG immunoglobulins in Iranian mothers. Methods: In total, 231 pregnant women and their paired infants enrolled in this study of which, 197 gave birth to fullterm and 26 gave birth to preterm, infants. Rubella specific antibodies were detected by an in-house whole-virus ELISA assay in maternal and cord sera of 188 fullterm and 26 preterm infants. Results: A highly significant correlation was observed between anti-rubella IgG in newborns in total, in preterm and fullterm neonates with their paired mothers (P-values=0.0001, 0.002, 0.0001, respectively). A borderline significant difference was observed between mean anti-rubella IgG in fullterm and preterm neonates (P=0.04). Mean cord/maternal ratio of anti-rubella IgG was 0.83 which was surprisingly low. A significant lower anti-rubella IgG was observed in newborns born from mothers with blood group B+ than those born from mothers with blood groups A+ (P=0.04) and O+ (P=0.02). respectively. The same difference was observed between mean maternal anti-rubella IgG in those with blood groups B+ and A+ (P=0.04) and those with blood groups B+ and O+ (P=0.05). In addition, a low frequency of B+ blood group in high positive sera and a high frequency of this blood group among low positive and negative sera was detected. Conclusions: Our data suggest that the main factors that influence the infants' rubella-specific IgG concentration are maternal concentration of this immunoglobulin, maternal blood group, and neonatal gestational age. (C) 2003 International Federation of Gynecology and Obstetrics. Published by Elsevier Science Ireland Ltd. All rights reserved.