The Proportion of Birth Asphyxia Associated With Maternal Heart Rate Artifact During Electronic Fetal Monitoring in Labour.

OBJECTIVES

This study aimed to estimate the proportion of birth asphyxia cases associated with delay in delivery (DD) due to maternal heart rate artifact (MHRA).

METHODS

This was a retrospective review of Canadian Medical Protective Association closed medico-legal cases of birth asphyxia from 2011 to 2020 in term labour, leading to hypoxic ischemic encephalopathy, cerebral palsy, or stillbirth. The final 2 hours of electronic fetal monitoring (EFM) were analyzed in 10-minute epochs by 3 independent experts using a template for evidence of MHRA judged to have resulted in DD. Records were also assessed for EFM classification, documentation of maternal pulse/MHRA, and labour factors.

RESULTS

Thirty-four cases of birth asphyxia were identified. Thirteen cases (38%) were found to have DD due to MHRA, of which 9 (69%) were in the second stage of labour. The average estimated DD was 44.2 ± 21.9 minutes. There was a lower proportion of time epochs with abnormal EFM in the 13 cases with DD versus 21 cases without DD (14.7% vs. 47.3%; OR 0.19 [0.11-0.33]; P < 0.002). Conversely, there was a higher proportion of MHRA (62.9% vs. 5.4%; OR 29.8 [15.5-57.3]; P = 0.002). The maternal pulse was documented in 34% versus 30%, respectively. Medical record review revealed no recognition by the caregivers of the occurrence of MHRA.

CONCLUSIONS

Unrecognized MHRA resulting in a falsely reassuring fetal heart rate, mainly in the active second stage, led to DD in more than one-third of birth asphyxia cases. These outcomes may be preventable by education and the routine use of technologies to detect MHRA.