The calcium binding protein, S100B, is increased in the amniotic fluid of women with intra-amniotic infection/inflammation and preterm labor with intact or ruptured membranes

Abstract

Objective: S100B is produced by glia of the central and peripheral nervous systems and is considered a marker of neurologic injury in the perinatal period. Indeed, increased neonatal urine S100B concentration is associated with adverse neurological outcomes including intraventricular hemorrhage and hypoxic-ischemic encephalopathy, while elevated adult serum concentrations are associated with infectious diseases/sepsis. The objective of this study was to determine whether amniotic fluid (AF) S100B concentrations change with advancing gestational age and intra-amniotic infection (IAI).

Study design: S100B concentration was measured in the AF of women in midtrimester, at term, and in pregnancies with preterm labor and intact membranes (PTL) or preterm premature rupture of membranes (PPROM), with and without IAI. Placental pathology was performed and neonatal outcomes were analyzed.

Results: (1) AF S100B concentration did not change during gestation; (2) patients with IAI had significantly higher AF S100B concentration than those without IAI following an episode of PTL or PPROM and; (3) neonates who had morbidity/mortality had had an elevated AF S100B concentration; however, this could be explained by the association with intra-amniotic infection/inflammation. Thus, AF S100B concentration was not an independent predictor of neonatal morbidity or fetal/neonatal death.

Conclusions: An elevated concentration of AF S100B may reflect intra-amniotic infection/inflammation and not necessarily fetal neurologic damage.

Figure 1

Amniotic fluid concentration of S100B according to pregnancy outcome and AF culture results. A) Among patients who delivered preterm, those with intra-amniotic infection had significantly higher S100B AF concentration [median: 1133.6 pg/ml (23.3−29,221.2)] than those who delivered preterm without IAI [median: 99.0 pg/ml (23.3−4731.9); p<0.05] or those who delivered at term [median: 51.0 pg/ml (23.3−130.0); p<0.05]. B) Similarly, the AF S100B concentration was significantly higher in patients with preterm PROM and IAI than in those without IAI [median and range: 98.3 pg/ml (23.3−19,922.5) vs. 49.0 pg/ml (23.3−17,683.7); p=0.018].

Figure 2

Amniotic fluid concentration of S100B in patients in preterm labor with intact membranes who subsequently delivered preterm neonates who underwent neurosonography. There was a significant difference in the AF S100B concentration between patients with PTL with and without IVH [median: 1305.1 pg/ml (122.1−29,221.2) vs. median: 113.7 pg/ml (23.3−13,842.2); p=0.005]. After excluding these 10 patients from the analysis, however, S100B AF concentration remained significantly higher in patients with PTL with IAI than those who delivered preterm without IAI [median and range: 865.9 pg/ml (23.3−13,842.2) vs. 91.3 pg/ml (23.3−4731.9); p=0.002].