At delivery, approximately 1 ml of cord blood from the infant's side will be collected in a sterile plastic screw-capped container, labeled and transported to the laboratory. Similarly 1 ml of venous blood will be obtained from the mother in a sterile plastic screw-capped container, labeled and transported to the laboratory. Serum will be separated from these samples by centrifugation and deep frozen at minus 20 degree C until analysis.