Can cardiotocography prior to induction of labour predict obstetric intervention? A pilot study

We set out to study the value of cardiotocography (CTG) performed before induction of labour for prolonged pregnancy in predicting obstetric intervention. This was a prospective observational study, based in a district general hospital. We studied 100 consecutive patients who underwent induction of labour for prolonged pregnancy. Cardiotocographs (CTGs) were performed before induction of labour on the tenth day after the estimated date of confinement (290 days). The CTGs were then reviewed without knowledge of the outcome of the induction of labour. Obstetric outcomes were then compared. The main outcome measures were the intrapartum presence or absence of meconium stained liquor and the necessity for obstetric intervention. Ninety per cent of CTGs were normal. There was no difference found between the two groups for operative delivery or the presence of meconium liquor. Caesarean section was more likely in the group with an abnormal CTG before induction of labour, but the possibility of this being due to chance is high in this study. There was one case of undiagnosed growth restriction in the abnormal CTG group. These results may be due to a true lack of difference in obstetric intervention between women with normal or abnormal CTGs prior to induction of labour or more probably an inability to detect a difference in our small study. These baseline data allow the calculations necessary for a more substantive trial.