Which definition corresponds to fetal tachycardia?

• A. Baseline FHR above 140 bpm for more than 5 minutes
• B. Baseline FHR above 160 bpm for more than 10 minutes
• C. Baseline FHR above 180 bpm for more than 20 minutes
• D. Baseline FHR above 120 bpm for more than 60 seconds

Answer: (B)

Fetal tachycardia is defined as a sustained elevation of the fetal baseline heart rate. The baseline is the average FHR over a 10-minute period, excluding accelerations or decelerations. When that baseline is greater than 160 beats per minute for more than 10 minutes, it meets the definition of tachycardia. This exactly matches the option describing a baseline above 160 bpm for more than 10 minutes, so it’s the correct choice. The other options either use a rate that's still within the normal range or apply durations that don’t align with the standard definition. Persistent tachycardia can signal maternal fever, fetal infection, anemia, or arrhythmias and requires clinical assessment.