Pertussis antibody titers in pregnant women's venous blood and cord blood—a survey from three women and children's hospitals in Beijing

Objective To study the levels of antibodies against bordetella pertussis among pregnant women and neonates in Beijing. Method From December 2016 to March 2017, pregnant women and their newborns from three women and children′s hospitals in Beijing were enrolled in this study. 3 ml of venous blood from the mothers and 3 ml of umbilical cord blood from neonates were drawn.Pertussis bacillus IgG antibody (PER-IgG) and pertussis toxin IgG antibody (PT-IgG) were tested using enzyme-linked immunosorbent assay. χ2 test was used to compare the positive rate of pertussis IgG antibodies in maternal and cord blood in the three hospitals. Correlational analyses of the antibodies levels in each hospital were conducted. The demographic characteristics, history of cough during pregnancy and history of DTaP vaccination of the mothers were collected via questionnaires. Result A total of 612 pairs of venous blood and cord blood samples were collected, including 4 mothers delivered twins and 616 cases of cord blood sample were collected. No history of pertussis were found in the 612 mothers. Among the 616 cases of umbilical cord blood, positive rate of PER-IgG was 13.3% (82/616), positive rate of PT-IgG was 0.5% (3/616). Among 612 cases of venous blood from the mothers, positive rate of PER-IgG was 7.7% (47/612), positive rate of PT-IgG was 0.3% (2/612). Positive rates of PER-IgG and PT-IgG in the mothers′ venous blood were not correlated with their residences (P=0.676 and 0.544). Positive rates of PER-IgG (r=0.842, P<0.001) and PT-IgG (r=0.619, P<0.001) in the mothers′ blood were positively correlated with the positive rate in umbilical cord blood. Conclusion This study shows that the positive rate of PER-IgG is very low in the maternal and umbilical cord blood in Beijing. Positive correlations of PER-IgG and PT-IgG between mother and umbilical cord blood were existed. Most mothers and their newborns do not have enough protection against pertussis. Key words: Whooping cough; Antibodies; Immunity; Cord blood; Maternal