Maternal smoking leads to increased cord serum IgG3

IgG subclass levels in cord serum of unselected European newborns were studied in relation to parental smoking. Cord IgG3 was significantly (P less than 0.01) higher in newborns of smoking mothers (n = 18; geom.mean = 87.0%) compared to those of non-smoking mothers (n = 66; geom.mean = 61.0%). Maternal smoking did not influence (P greater than 0.10) cord IgG2 or cord IgG4. Paternal smoking did not affect any of the three immunoglobulins in cord serum (P greater than 0.10). These data suggest that tobacco smoking affects IgG3 synthesis in some direct or indirect way.