Objective: Elevated levels of inflammatory cytokines in the fetus have been linked to neurologic morbidities in preterm neonates. Magnesium sulfate is currently being studied in clinical trials as a potential fetal neuroprotective agent. The purpose of this study was to determine whether intrapartum magnesium sulfate therapy has an effect on the umbilical venous concentrations of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha at delivery.
Study design: Women with singleton gestations >32 weeks with no clinical indications for magnesium sulfate therapy (preeclampsia or tocolysis) and either clinical chorioamnionitis or prolonged rupture of membranes were recruited for the study. Consenting patients were randomly assigned, in a double-blinded fashion, to receive either magnesium sulfate (6-g load then 2 g/hr) or matched volumes of lactated Ringer's solution until delivery. Fetal blood specimens were obtained by aspiration of the umbilical vein after cord clamping but before placental separation. Umbilical cytokine levels were measured with a sensitive and specific immunoassay.
Results: Twenty-two patients were randomly assigned to groups and received either magnesium sulfate (n = 11) or placebo (n = 11). There were no differences in the demographic or clinical characteristics between groups. The umbilical venous ionized magnesium concentration was significantly higher in the magnesium sulfate group (2.32 +/- 0.27 mg/dL vs 1.23 +/- 0.15 mg/dL; P <.001). There were no statistically significant differences between groups with respect to umbilical levels of interleukin-1beta (1.5 pg/mL [1.5-58] vs 1.5 pg/mL [1.5-10]; P =.5); interleukin-6 (8.5 pg/mL [1-1000] vs 11.2 pg/mL [1-113]; P =.9); or tumor necrosis factor-alpha (16 pg/mL [7.6-20.3] vs 16.6 pg/mL [8.3-22.2]; P =.5).
Conclusion: In this pilot study the intrapartum administration of magnesium sulfate does not appear to affect the concentration of inflammatory cytokines in fetal blood at delivery.