Clinical significance of suspicious antepartum cardiotocograms: a study of normal and high-risk pregnancies.

Analysis of 594 antepartum cardiotocograms (CTGs) from 91 strictly normal pregnancies and of 2770 CTGs from 405 high-risk pregnancies showed a suspicious pattern in 7.2 and 17.4 per cent respectively. Careful analysis of these CTGs shows that they cannot be considered as either normal or abnormal, whereas their value for predicting the outcome of pregnancy is too limited to be of a direct clinical significance. Although their characteristics vary little between normal and high-risk pregnancy, their recurrence rate is much higher in high-risk pregnancy. During high-risk pregnancy this pattern was obtained on at least two consecutive recordings in 13.3 per cent and on at least three consecutive recordings in 6.2 per cent of patients, as compared to respectively 3.3 and 1.1 per cent during normal pregnancy. Although a single or even repeat occurrence of a suspicious CTG does not justify intervention during pregnancy, our study shows that an adequate follow-up of repeat CTGs will usually be able to distinguish pregnancies that are in need of intervention from those that are not.