Standard External Doppler Fetal Heart Tracings versus External Fetal Electrocardiogram in Very Preterm Gestation: A Pilot Study

Introduction  Very preterm babies can be difficult to monitor using standard external Doppler fetal heart tracings (eFHR). External fetal electrocardiogram (fECG) is a potential alternative. Methods  This was a prospective observational pilot study of hospitalized patients at 24 to 28 weeks' gestation. A total of 30 women were traced for up to 2 hours using eFHR followed by up to 2 hours using fECG. The percentage of time the fetal heart rate was traced during the 2-hour window for each modality was calculated. Differences of ≥ 60, ≥ 80, and ≥ 90% total time traced were compared between modalities using McNemar's test. Differences were also assessed for each method between nonobese (body mass index [BMI]  2 ) and obese (BMI ≥ 30 kg/m 2 ) women using chi-square and Fisher's exact tests. Results  Superior performance was found with eFHR at ≥ 60% (93.3 vs. 46.7%, p p p p  = 0.017). Conclusion  With current technology fECG performance in very preterm gestation was worse than conventional eFHR, although fECG may have a role in nonobese patients.