Cherry JD, Gornbein J, Heininger U, et al. 6 weeks, 11% (9/81) of babies were expected to have potentially protective antibody levels. Using cluster analysis, 9% (7/81) of mothers experienced evidence of earlier pertussis infection. Babies created to these mothers were expected to be more likely to have potentially protecting antibodies at 6 weeks (43%) than those created to mothers without (8%) (p = 0.03). Summary Approximately 75% of babies were created with pertussis antibody levels lower than the moderate levels associated with potential safety. Despite effective antibody transfer, nearly 90% of babies were expected to have little antibody by 6 weeks. Maternal immunization before or during pregnancy might simulate earlier pertussis illness and help TZ9 guard infants through the first months of life. INTRODUCTION Pertussis, an endemic and common infectious disease, is usually of particular importance due to a recent striking increase in the incidence of reported cases and best morbidity and mortality in the youngest infants.1C3 In 2004C2005, a total of 56 deaths from pertussis in children younger than 3 months were reported to the Centers for Disease Control and Prevention (CDC).4 Because infants do not complete the primary immunization series against pertussis until their sixth month of life, they are particularly susceptible to pertussis infection and are dependent on SPN maternal antibodies for protection.5 Although precise levels of antibody required for protection from acute pertussis infection have been debated,1,2 modest levels of IgG antibody to fimbriae (FIM), pertactin (PRN) and pertussis toxin (PT) have been associated with disease prevention.6,7 Although filamentous hemagglutinin (FHA) is a component of all licensed pertussis vaccines and antibody against FHA is associated with natural infection, it has not been proven to play a primary role TZ9 in prevention of pertussis infection.6C9 Several articles have postulated that immunizing pregnant women against pertussis may provide protection to their newborns, 10C13 but the CDCs Advisory Committee on Immunization Practices (ACIP) does not currently recommend this practice.14 Previous studies have also shown that infants given birth to at or near term have higher antibody levels to specific pathogens than their mothers as a result of active transfer of maternal IgG.15,16 A better understanding of the natural history of transplacentally acquired pertussis antibodies in infants is critical for predicting whether maternal immunization might provide protection from infection to newborns. To further elucidate the potential of maternal pertussis antibody to provide protection against pertussis for newborns in the months before their scheduled active immunization, the objectives of our study were to 1 1) determine the proportion of mothers and infants who experienced levels of IgG antibody to pertussis antigens predicted to be potentially protective at delivery; 2) evaluate the efficiency of maternal-infant antibody transport; 3) extrapolate infant antibody titers at 6 weeks, and 4) identify maternal factors associated with potentially protective infant antibodies. METHODS Protection of human subjects Approval to conduct this study was granted by the Institutional Review Boards of the University or college of New Mexico and the University or college of Utah. Mothers provided informed consent for themselves and their infants. Study subjects Women aged 18C45 years of age who delivered healthy term infants 37 weeks gestation were enrolled from your University or college of New Mexico Health Sciences Center from February 2006 through April 2007. Mother-infant pairs were excluded for multiple gestation, antenatal detection of a major birth defect in the TZ9 infant, or serious underlying neurological, cardiac, renal, or pulmonary disease in either mother or infant. Mother-infant pairs were also excluded if the infant required neonatal rigorous care. Data collection Participants were enrolled by the University or college of New Mexico General Clinical Research Center (GCRC) pediatric research nurses within 48 h after delivery and before hospital discharge. Demographic data included age, previous pregnancy history, occupation, education, ethnicity, marital TZ9 status, and number of people in the household. In addition, a history of cough greater than 3 weeks in either mother or any household contact during the pregnancy was obtained. Women enrolled in 2007 (n=17) were asked whether they experienced received pertussis vaccine (Tdap). Immunization status was not documented for ladies enrolled in 2006 Laboratory methods 2 ml each of maternal and infant sera were collected by venipuncture, centrifuged and stored TZ9 at ?20 to ?40 C, until screening by a standardized enzyme-linked immunosorbent assay (ELISA) in the.