Assessment of antepartum cardiotocograms in high-risk pregnancy.

Abstract

A ten-point scoring system was used to assess 2770 antepartum cardiotocograms (CTGs) obtained in 405 pregnancies at risk. There were 284 pregnancies with a last CTG within 24 hours before labour, Caesarean section or intrauterine death; these were analysed separately and their outcome correlated well with the last CTG score, better than with individual CTG criteria. The relationship between CTG score and fetal condition at birth was particularly close for pregnancies with growth retardation, rhesus isoimmunisation or hypertension. A score of 8 to 10 reliably predicted good condition at birth in 95 per cent of pregnancies which ended within 24 hours and in 88 per cent of those which ended after three or four days. A score of 5 points or less invariably indicated poor fetal condition with little chances of a normal outcome unless the cause could be effectively treated. The score provides a highly specific but moderately sensitive test for fetal well-being with virtually no false positive and only few false negative results. However, almost 15 per cent of CTGs, scoring 6 or 7 points, provide too little information on fetal well-being to be of clinical value.