The significance of meeting Dawes-Redman criteria in computerised antenatal fetal heart rate assessment.

OBJECTIVE

To investigate the significance of not meeting Dawes-Redman criteria on computerised cardiotocography in high-risk pregnancies.

DESIGN

Retrospective observational study.

SETTING

UK university hospital.

POPULATION: High-risk pregnancies undergoing antenatal assessment.

METHODS

We interrogated the database for records of computerised fetal heart rate assessment and pregnancy outcomes.

MAIN OUTCOME MEASURES: Neonatal outcome and stillbirths.

RESULTS

Excluding duplicate assessment in the same pregnancy, 14 025 records with complete information on the criteria of normality having been met and the outcome of the pregnancy were available. Criteria were not met for 907 records (6.46%). The gestational age of assessment was lower in the group not meeting criteria of normality. Overall, 32 stillbirths occurred in normally formed fetuses (2.28/1000). Stillbirths were more frequent in the group not meeting criteria (odds ratio [OR] 8.78, 95% CI 4.28-18.02). This finding persisted even after records with abnormally low short-term variation (STV) were excluded. The confidence intervals around the rate of stillbirth in the two groups overlapped beyond an STV of 8 ms.

CONCLUSIONS

Approximately 1:16 pregnancies do not meet the criteria of normality. The criteria are not met more often at preterm gestation than at term. The risk of stillbirth was higher in the group not meeting criteria of normality, even if cases with low STV are excluded. Cases not meeting criteria should be followed up closely, unless the STV is ≥8 ms. Stillbirths still occurred in the group meeting criteria, but the rate was lower than in the general population.