• Ayesha M F Heinis, Marc E Spaanderman, Jacqueline M T Klein Gunnewiek, and Fred K Lotgering.
• Department of Obstetrics and Gynecology Department of Clinical Chemistry, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. a.heinis@obgyn.umcn.nl
• Acta Obstet Gynecol Scand. 2011 Oct 1; 90 (10): 1107-14.

ObjectiveTo study to what extent the fetal scalp blood lactate concentration during labor correlates with fetal scalp pH and base deficit, and metabolic acidosis at birth, and to suggest lactate cut-off values to serve as indicators for either reassurance or immediate intervention.DesignA retrospective observational study.SettingLabor ward at a university medical center.SampleFetal scalp and cord blood samples with acid-base and lactate values from 486 singleton pregnancies beyond 34 weeks' gestation.MethodsThe relation between lactate, pH and base deficit (BD) in fetal scalp blood was tested by Spearman's rho correlation coefficient. Lactate cut-off values indicating either reassuring fetal status or immediate intervention were estimated using percentile distribution and compared with pH and BD.Main Outcome MeasuresMetabolic acidosis, defined as umbilical cord artery pH below 7.05 and BD calculated for the blood compartment above 12 mmol/l.ResultsAfter 127 (21%) exclusions, 486 cases were available for analysis. Fetal lactate values increased with evolving metabolic acidosis. Lactate concentration correlated with both pH (r=-0.50, p<0.01) and BD (r=0.48, p<0.01). Lactate <5.4 mmol/l indicated reassuring fetal status, whereas lactate ≥6.6 mmol/l indicated metabolic acidosis. Fetal lactate correlated better with either the absence or presence of metabolic acidosis at birth than did fetal pH and BD.ConclusionsIn the case of a non-reassuring fetal heart rate, fetal scalp blood lactate provides more accurate information on fetal acid-base status than does pH and/or BD.© 2011 The Authors Acta Obstetricia et Gynecologica Scandinavica© 2011 Nordic Federation of Societies of Obstetrics and Gynecology.

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