Intrapartum Resuscitation Interventions for Category II Fetal Heart Rate Tracings and Improvement to Category I.

Objective: To evaluate intrapartum resuscitation interventions and improvement in category II fetal heart rate (FHR) tracings.
Methods: This secondary analysis of a randomized trial of intrapartum fetal electrocardiographic ST-segment analysis included all participants with category II FHR tracings undergoing intrauterine resuscitation: maternal oxygen, intravenous fluid bolus, amnioinfusion, or tocolytic administration. Fetal heart rate pattern-recognition software was used to confirm category II FHR tracings 30 minutes before intervention and to analyze the subsequent 60 minutes. The primary outcome was improvement to category I within 60 minutes. Secondary outcomes included FHR tracing improvement to category I 30-60 minutes after the intervention and composite neonatal outcome.
Results: Of 11,108 randomized participants, 2,251 (20.3%) had at least one qualifying intervention for category II FHR tracings: 63.7% improved to category I within 60 minutes and 50.5% improved at 30-60 minutes. Only 3.4% underwent cesarean delivery and 4.1% an operative vaginal delivery for nonreassuring fetal status within 60 minutes after the intervention. Oxygen administration was the most common intervention (75.4%). Among American College of Obstetricians and Gynecologists-defined subgroups that received oxygen, the absent FHR accelerations and absent-minimal FHR variability subgroup (n=332) was more likely to convert to category I within 60 minutes than the FHR accelerations or "moderate FHR variability" subgroup (n=1,919) (77.0% vs 63.0%, odds ratio [OR] 2.0, 95% CI 1.4-2.7). The incidence of composite neonatal adverse outcome for category II tracings was 2.9% (95% CI 2.2-3.7%) overall; 2.8% (95% CI 2.0-3.8%) for improvement to category I within 60 minutes (n=1,433); and 3.2% (95% CI 2.1-4.6%) for no improvement within 60 minutes (n=818). However, the group with improvement had 29% lower odds for higher level neonatal care (11.8% vs 15.9%, OR 0.71, 95% CI 0.55-0.91).
Conclusion: Nearly two thirds of category II FHR tracings improved to category I within 60 minutes of intervention with a relatively low overall rate of the composite neonatal adverse outcome.
Funding Source: Funded in part by Neoventa Medical.
Competing Interests: Financial Disclosure Alan Tita reports his institution received funds from Pfizer. Russell Miller reports money was paid to him from Janssen Research & Development, LLC, for serving on their Advisory Board service (unrelated to this manuscript topic). He also received funds from UpToDate (chapter author unrelated to this manuscript topic). David McKenna's institution is a satellite site for The Ohio State University for the NICHD MFMU, which pays his institution for patients enrolled in MFMU studies. Edward Chien reports that money was paid to his institution from MetroHealth. The other authors did not report any potential conflicts of interest.
(Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)