In the first stage of labor with external fetal monitoring, which pattern on the fetal heart tracing suggests adequate uteroplacental-fetal perfusion?

• A. Late decelerations
• B. Fetal heart rate accelerations
• C. Prolonged decelerations
• D. Tachycardia

Answer: (B)

The key idea is that accelerations on the fetal heart tracing signal good fetal oxygenation and placental blood flow. When the fetus moves or experiences mild autonomic responses, the heart rate briefly speeds up by a meaningful amount (typically 15 beats per minute or more above baseline for 15 seconds or longer, depending on gestational age). In the first stage of labor with external monitoring, the presence of these accelerations is a reassuring sign that uteroplacental perfusion is adequate and the fetus is well-oxygenated.

In contrast, late decelerations appear after a contraction peaks and point to uteroplacental insufficiency during contractions, indicating reduced oxygen delivery. Prolonged decelerations reflect more prolonged or severe hypoxia and are concerning. Tachycardia can occur with infection, fever, or distress but does not specifically indicate adequate perfusion. So the pattern suggesting adequate uteroplacental-fetal perfusion is fetal heart rate accelerations.