Elevations of amniotic fluid macrophage inflammatory protein-1α concentrations in women during term and preterm labor

To determine whether elevated concentrations of macrophage inflammatory protein-1α (MIP-la) in amniotic fluid (AF) are related to term and preterm labor. Amniotic fluid was obtained from women from five different clinical situations: 1) term cesarean delivery, no labor ( n = 29); 2) normal term labor, no infection ( n = 36); 3) preterm labor, delivery more than 1 week from sampling, no infection ( n = 19); 4) preterm labor, delivery within 1 week from sampling, no infection ( n = 18); and 5) preterm chorioamnionitis ( n = 8). Amniotic fluid was collected aseptically at the time of amniocentesis, amniotomy, or hysterotomy. Concentrations of MIP-1α were determined by enzyme-linked immunosorbent assay. Statistical analysis was by Wilcoxon rank-sum test, Kruskal-Wallis test, and unpaired t test. Women in normal term labor had significant elevations of AF MIP-1α concentrations when compared with women at term undergoing repeat cesarean delivery ( P < .001). In women with term gestation, AF MIP-1α correlated well with cervical dilation ( r 2 = 0.479, P < .001). In women with preterm labor who later delivered within 1 week of presentation, AF MIP-1α concentrations were higher than those from women who did not deliver within 1 week. Women who presented with clinically evident chorioamnionitis had the highest concentrations of AF MIP-1α ( P = .001). Women in labor have significantly elevated AF concentrations of MIP-1α, particularly if labor is associated with intrauterine infection. We suggest that MIP-1α is involved in the physiology of normal labor and in the pathogenesis of infection-associated preterm labor.