S100B protein cord blood levels and development of fetal behavioral states: a study in normal and small-for-dates fetuses

OBJECTIVE: We aimed to determine whether S100B protein levels in cord blood and the development of fetal behavioral states were altered and interrelated in small-for-dates (SFD) fetuses. METHODS: Umbilical cord blood samples were collected from 12 SFD fetuses with normal umbilical artery (UA) Doppler findings, from six SFD fetuses with abnormal Doppler waveform patterns and from 36 controls matched for gestational age. S100B protein levels were measured by means of a specific radioimmunoassay. Fetal behavioral state recordings were made before delivery by Cesarean section and data were expressed as percentage of quiet sleep coincidence (C1F), of activity state coincidence (C2-4F) and of no coincidence (NOC). Flow velocimetry waveforms were recorded from the uterine artery, UA and fetal middle cerebral artery (MCA). RESULTS: Mean S100B protein levels in umbilical plasma were significantly higher in the six SFD infants with abnormal prenatal Doppler findings (3.31 +/- 0.65 microg/l) than in SFD infants with normal Doppler findings (1.56 +/- 0.35 microg/l) and in controls (1.23 +/- 0.43 microg/l). Similarly in these fetuses NOC was higher and C2F significantly lower (p < 0.05), but there was no significant difference in C1F. S100B concentrations were correlated with the UA pulsatility index (PI) (r = 0.78, p < 0.01), with the MCA PI (r = -0.78, p < 0.01) and with the UA PI/MCA PI ratio (r = 0.80, p < 0.01). Also, NOC and C2F percentages were correlated with the UA PI (r = 0.61, p < 0.01 and r = -0.61, p < 0.01, respectively), with the MCAPI (r = -0.72, p < 0.001 and r = 0.66, p < 0.01, respectively), and with the UA PI/MCA PI ratio (r = 0.60, p < 0.01 and r = -0.54, p < 0.05, respectively). NOC was also correlated with S100B protein (r = 0.48, p < 0.05); the correlation of S100B protein and C2F almost reached significance (r = -0.47, p < 0.05). CONCLUSIONS: This study provides evidence of a relationship between a biochemical marker of brain development and/or integrity and the development of fetal behavioral states, offering additional information on brain maturation in normal and high-risk pregnancies.