• M Melin, A Bonnevier, M Cardell, L Hogan, and A Herbst.
• Department of Obstetrics and Gynaecology, Clinical Sciences, Lund University Hospital, Lund, Sweden.
• BJOG. 2008 Dec 1; 115 (13): 1669-75.

ObjectiveTo assess the occurrence of ST-interval segment changes of the fetal electrocardiogram (ECG) and cardiotocographic (CTG) abnormalities preceding acidaemia at birth.DesignCase-control study.SettingUniversity hospital labour ward.SampleNewborns with severe cord artery metabolic acidaemia (pH < 7.00 and lactate > or = 10 mmol/l; n= 24), moderate metabolic acidaemia (pH 7.00-7.09 and lactate > or = 10; n= 48), acidaemia (pH 7.00-7.09; n= 52), pre-acidaemia (pH 7.10-7.19; n= 265), and controls (pH > or = 7.20; n= 117).MethodsMonitoring traces were assessed blinded to outcome.Main Outcome MeasuresCTG and ST changes.ResultsAny ST event occurred significantly more often among cases with severe (79%) and moderate (75%) metabolic acidaemia than among controls (50%). The difference was restricted to baseline T/QRS rises and to the second stage of labour, during which any event only occurred significantly more often among cases with severe metabolic acidaemia (62%) than among controls (38%). ST events coincided with abnormal CTG patterns in 67, 44, 40, and 28% of cases with severe and moderate metabolic acidaemia, acidaemia, and pre-acidaemia, respectively, and in 12% of controls. ST events with intermediary CTG were similarly frequent in the case groups (0-6%) as in the controls (4%). The ST guidelines stated intervention in 96, 62, 73, and 49% of case groups and 23% of controls.ConclusionsOnly two of three cases with severe and less than half of cases with moderate metabolic acidaemia were preceded by ST events coinciding with CTG abnormalities. It is therefore important to intervene for long-lasting, rapidly deteriorating or marked (preterminal) CTG abnormalities, also in the absence of ST events.

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