THE INCIDENCE OF ABNORMAL FINDINGS FROM INTRAPARTUM CARDIOTOCOGRAM MONITORING IN TERM AND PRETERM LABORS

A retrospective analysis of 514 consecutive labours delivering 530 bab ies over a period of 18 months was conducted by a high-risk pregnancy team in a tertiary teaching unit to compare the incidence of abnormal findings from intrapartum monitoring between labours occurring before and at or after 34 weeks' gestation. Those delivered by elective Caesa rean section, or Caesarean section at the onset of labour because of c ontraindications to labour and vaginal delivery, and those with congen itally malformed fetuses were excluded. Tracings were scored using the FIGO 1987 guidelines. Seventy-four labours and 83 babies delivered be fore 34 weeks, and 340 labours and 447 babies delivered after 34 weeks in the study. There was a slightly higher incidence of suspicious CTG tracings (33.7% versus 19.6%, OR 2.66, 95% CI 1.6-4.4) in the preterm group, due mainly to decreased baseline variability (p<0.001, OR 3.57 , 95% CI 1.8-6.9), but the incidence of other pathological patterns di d not differ. Using the same set of criteria for interpretation, there was a higher incidence of abnormalities from continuous cardiotocogra m monitoring in the preterm group compared to term labours, but the in tervention rate for fetal distress was not significantly increased. Ap propriate interpretative criteria for intrapartum monitoring of preter m labours should be devised.