Continuous electronic fetal heart monitoring versus intermittent auscultation during labor: Would the literature outcomes have the same results if they were interpreted following the NICHHD guidelines?

BACKGROUND

All guidelines regarding electronic fetal heart monitoring (EFM) before 2008 were designed to avoid more hypoxia than acidosis. In addition, the results of the Cochrane meta-analysis of 2013 do not show a significant improvement in neonatal outcomes using EFM or intermittent auscultation (IA).

OBJECTIVES

We retrospectively evaluated the results on delivery outcomes arising from a comparison between EFM and IA during labor of 2 specific and high-quality trials. We hypothesized that revisiting the delivery outcomes through the adoption of the recent National Institute of Child Health and Human Development (NICHHD) guidelines, the reported delivery outcomes would be different.

MATERIAL AND METHODS

The study retrospectively evaluated the results on delivery outcomes arising from the comparison between EFM and IA during labor of the "Dublin trial" and "Vintzileos trial" published, respectively, in 1985 and 1993. A translational model was constructed to recalculate these results, applying a correction factor to estimate the number of pathological patterns using the NICHHD guidelines for EFM.

RESULTS

After the reevaluation of the 2 trials using the proposed correction factor, the comparison of the recalculated cesarean section and operative delivery rates for fetal distress between EFM and IA group were no longer statistically significant, both in the Dublin trial and Vintzileos trial. Even the comparison of the recalculated incidence of the rate of non-reassuring fetal heart rate (FHR) patterns in the EFM and IA groups has not given any indication of significance for the Vintzileos trial.

CONCLUSIONS

Our results lead to reconsidering the results of the Dublin trial and Vintzileos trial in terms of operational rates of births, hypothesizing that these results would have been significantly lower if FHR traces were interpreted using the current NICHHD guidelines, which aim to identify potential acidotic fetuses rather than hypoxic ones.