Validation of a Handheld Fetal Heart Rate Monitor Against Cardiotocography in a Nigerian Primary Care Setting: A Diagnostic Accuracy Study

**Abstract** In low-resource primary care settings, access to standard cardiotocography (CTG) for antenatal fetal surveillance is often unavailable. Handheld Doppler devices present a pragmatic alternative, but their diagnostic accuracy in routine practice requires rigorous, context-specific validation. This study aimed to evaluate the diagnostic accuracy of a handheld fetal heart rate (FHR) monitor against standard CTG for identifying normal and abnormal FHR patterns during the third trimester in Nigerian primary healthcare centres. A cross-sectional diagnostic accuracy study was conducted across multiple primary health centres in Enugu State, Nigeria. A consecutive sample of 350 pregnant women in their third trimester underwent simultaneous FHR monitoring using a handheld Doppler device and a standard CTG machine. All assessments were performed by trained midwives. CTG traces were interpreted by a blinded obstetrician as the reference standard. Sensitivity, specificity, positive predictive value (PPV), and agreement statistics were calculated. Compared to CTG, the handheld device demonstrated a sensitivity of 92% and a specificity of 86% for detecting abnormal FHR patterns, with a PPV of 78%. The mean difference in FHR measurement between devices was 3.2 beats per minute, indicating good agreement. The handheld FHR monitor showed good diagnostic accuracy for routine antenatal assessment in a primary care setting. It represents a clinically useful tool for initial screening, potentially improving access to basic fetal surveillance. Integration into routine care is supported, with recommendations for healthcare worker training and a protocol whereby abnormal readings prompt referral for confirmatory CTG. **Keywords:** fetal heart rate monitoring, cardiotocography, diagnostic accuracy, primary health care, Nigeria, antenatal care, handheld Doppler