Diagnostic value of the unstressed antepartum cardiotocogram

The unstressed antepartum cardiotocogram (CTG) is principally judged by two aspects: baseline irregularity, and reaction to Braxton Hicks contractions and fetal movements. A classification into normal, sub-optimal, decelerative, and terminal CTG was devised. The ominous significance of the terminal CTG was confirmed in 26 patients; nine of the fetuses died in utero and the other 17 were delivered by elective Caesarean section; only one newborn was neither small-for-dates nor acidaemic. The significance of the other three categories was evaluated in 428 patients in whom labour was induced. All patients with repeated decelerative antepartum CTG showed signs of fetal distress during labour and most of them required Caesarean section; patients with a normal or sub-optimal CTG rarely showed signs of fetal distress during labour. The incidence of growth retardation was 41 per cent in the combined decelerative and sub-optimal groups against 9 per cent in the normal group. In comparing these results with studies of the oxytocin challenge test, it was concluded that, except in the case of a sub-optimal CTG, the oxytocin challenge test has no place in obstetrics.