Abstract
Background
Fetal stethoscopes are mainly used for intermittent monitoring of fetal heart rate (FHR) during labor in low-income countries, where perinatal mortality is still high. Handheld Dopplers are rarely available and are dependent on batteries or electricity. The objective was to compare the Pinard stethoscope versus a new wind-up handheld Doppler in the detection of abnormal FHR.
Materials and methods
We conducted a randomized controlled study at Muhimbili National Hospital, Tanzania, from April 2013 to September 2015. Women with gestational age ≥37 weeks, cephalic presentation, normal FHR on admission, and cervical dilatation <7 cm were included. Primary outcome was abnormal FHR detection (<120 or >160 beats/min). Secondary endpoints were time to delivery, mode of delivery, and perinatal outcomes. χ2, Fisher’s exact test, Mann–Whitney test, and logistic regression were conducted. Unadjusted and adjusted odds ratios were calculated with respective 95% confidence interval.
Results
In total, 2,844 eligible women were assigned to FHR monitoring with Pinard (n=1,423) or Doppler (n=1,421). Abnormal FHRs were more often detected in the Doppler (6.0%) versus the Pinard (3.9%) arm (adjusted odds ratio =1.59, 95% confidence interval: 1.13–2.26, p=0.008). Median (interquartile range) time from abnormal FHR detection to delivery was comparable between Doppler and Pinard, ie, 80 (60,161) and 89 (52,165) minutes, respectively, as was the incidence of cesarean delivery (12.0% versus 12.2%). The incidence of adverse perinatal outcomes (fresh stillbirths, 24-hour neonatal admissions, and deaths) was similar overall; however, among newborns with abnormal FHR delivered vaginally, adverse outcomes were less incident in Doppler (7 of 43 births, 16.3%) than in the Pinard arm (10 of 23 births, 43.5%), p=0.021.
Conclusion
Intermittent FHR monitoring using Doppler was associated with an increased detection of abnormal FHR compared to Pinard in a low-risk population. Time intervals from abnormal FHR detection to delivery were longer than recommended in both arms. Perinatal outcomes were better among vaginally delivered newborns with detected abnormal FHR in the Doppler arm.
Acknowledgments
We thank the hospital administration for allowing us to use the hospital facilities to collect data for this study. We also wish to acknowledge the entire midwife team for the excellent job of keeping records of all deliveries in the midwifery book that was then computerized. We thank the well-motivated data clerks of the Safer Births project for data entry and cleaning. The Laerdal Foundation funded the study. The funder had no role in the study design, data collection, analysis, or decision to publish or preparation of the manuscript.
Disclosure
BAK received unconditional funding for studies from Laerdal Foundation. The other authors report no conflicts of interest in this work.
Author contributions
BAK conducted the initial statistical data analysis and prepared all sections of the first draft and compiled the final manuscript. HLK conceived and designed the study and supervised the training of research midwives and the data collection process. He was also involved in data analysis and the interpretation of the results. PJW and ERM participated in the design of the study and the review of the manuscript. ID reviewed the statistical analysis and the final draft of the manuscript. HLE and JMP were involved in design of the study, interpretation of data, and critically reviewed the manuscript. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work. All authors agreed on the final submitted manuscript.