SECRETORY COMPONENT OF IMMUNOGLOBULIN-A IN MATERNAL SERUM AND THE PREDICTION OF PRETERM DELIVERY

OBJECTIVE: Our purpose was to determine whether the secretory componen t of immunoglobulin A in maternal serum predicts delivery before 34 we eks' gestation. STUDY DESIGN: Primigravid women of an urban population in New Zealand were recruited at booking into a prospective longitudi nal nested case control study (n = 1651;after exclusions and withdrawa ls, n = 1511). Serum was collected at 8 to 12 weeks, 15 to 18 weeks, 2 1 to 24 weeks, 28 to 30 weeks, and 36 to 38 weeks of gestation and 6 w eeks post partum. Concentrations of the secretory component of immunog lobulin A were determined by enzyme-linked immunosorbent assay in all women who were delivered preterm (n = 53) and in controls randomly sel ected from women delivered at less than or equal to 37 weeks' gestatio n (n = 178). RESULTS: Serum concentrations of the secretory component of immunoglobulin A were similar in women delivered at term or preterm throughout pregnancy (n = 21 delivered at <34 weeks and n = 32 at 34 to 36.9 weeks, incidence 3.5%). Receiver-operator characteristic curve s showed no discriminating ability of the secretory component of immun oglobulin A. Smokers had 50% higher concentrations than nonsmokers did (p < 0.0001 by analysis of variance). CONCLUSION: The secretory compo nent of immunoglobulin A in maternal serum does not predict preterm de livery in a low-risk population.