The transplacental transfer of IgG subclasses: influence of prematurity and low birthweight in the Gambian population

Having established previously that prematurity in The Gambia is associated with impaired materno-fetal transfer of some specific antibodies, we investigated the influence of low birthweight and prematurity on placental transfer of IgG subclasses in 180 Gambian mothers and their newborn babies. A physician-blinded, cross-sectional study of 180 mother-baby pairs was carried out in the labour ward of Bansang Hospital, The Gambia. Paired maternal and cord serum samples were collected from mothers and their newborns. Serum IgG subclass levels were measured by laser nephelometry. Placental transfer of all IgG subclasses was significantly reduced in preterm newborns compared with term newborns (p < 0.01). In low birthweight (LBW) babies, the transfer of IgG(1) (p = 0.03) and IgG(2) (p < 0.01) subclasses, but not IgG(3) and IgG(4), was significantly reduced. In preterm. neonates with an adequate birthweight and term neonates with a low birthweight, all IgG subclasses were transferred with reduced efficiency, but IgG(1) and IgG(2) subclasses were transferred with significantly less efficiency than IgG(3) and IgG(4). These results confirm that prematurity and low birthweight are associated with impaired placental transfer of IgG(1) and IgG(2) subclasses in this Gambian population. This impairment might explain the susceptibility of these newborns to certain polysaccharide-encapsulated organisms.