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Difficulty: MediumObstetric Complications

A 24-year-old G1P0 woman at 39 weeks of gestation is evaluated in the labor suite. She was admitted 4 hours ago in spontaneous active labor and is currently not receiving any medications. Her temperature is 37.1°C (98.8°F), blood pressure is 118/72 mm Hg, pulse is 88/min, and respirations are 16/min. Physical examination reveals mild bilateral lower extremity pitting edema and a grade 2/6 systolic ejection murmur at the left sternal border. The cervix is 6 cm dilated and 90% effaced, with the fetal vertex at 0 station. Fetal heart rate monitoring demonstrates a baseline of 140/min with moderate variability. Over the last 30 minutes, there are recurrent, symmetric decreases in the fetal heart rate that begin gradually with the onset of each uterine contraction, reach their nadir of 120/min exactly at the peak of the contraction, and return to the baseline as the contraction ends. Which of the following is the most appropriate next step in management?

  1. A
    Reposition the patient and administer an intravenous fluid bolus
  2. Continue routine expectant management of laborAnswer
  3. C
    Administer intravenous magnesium sulfate
  4. D
    Prepare for immediate cesarean delivery
  5. E
    Administer intravenous terbutaline

Answer

The correct answer is to continue routine expectant management of labor, as the patient has normal physiologic changes of pregnancy and a reassuring fetal heart rate tracing.
This patient has a reassuring Category I fetal heart rate (FHR) tracing characterized by a normal baseline, moderate variability, and early decelerations. Early decelerations are symmetrical, gradual decreases in the FHR that perfectly mirror uterine contractions—meaning the nadir of the deceleration occurs simultaneously with the peak of the contraction. They are caused by physiologic fetal head compression during contractions, which alters cerebral blood flow and triggers a benign vagal response. Because this is a normal finding in active labor, no acute intervention is required, and continuing routine expectant management is the correct next step. Furthermore, her mild peripheral edema and grade 2/6 systolic ejection murmur are normal physiologic adaptations to pregnancy (arising from increased plasma volume and decreased systemic vascular resistance) and do not represent a pathological complication.

Step-by-Step Solution

1
Evaluate the maternal vital signs and physical examination findings.
The blood pressure is normal (118/72 mm Hg). The mild lower extremity edema and systolic ejection murmur are identified as benign, physiologic adaptations to pregnancy.
Differentiating normal physiologic changes of pregnancy from pathological states (like preeclampsia or heart failure) prevents unnecessary and potentially harmful interventions.
2
Interpret the fetal heart rate (FHR) tracing.
The baseline is 140/min, variability is moderate, and decelerations exactly mirror the uterine contractions (the nadir aligns with the peak of the contraction).
Accurate interpretation of the FHR tracing is required to classify it into a specific category and determine fetal well-being.
3
Identify the etiology of the FHR decelerations based on the timing relative to contractions.
The pattern describes early decelerations, which are caused by physiologic fetal head compression altering cerebral blood flow and triggering a benign vagal response.
Understanding the pathophysiology of decelerations dictates the clinical response. Early decelerations are normal and part of a Category I tracing.
4
Determine the appropriate clinical intervention.
Because both the maternal clinical status and the fetal tracing are reassuring, no acute intervention is required.
A Category I tracing indicates normal fetal acid-base status and warrants routine expectant management.

Key Concept

Early fetal heart rate decelerations (symmetrical decreases mirroring contractions) are a benign finding caused by fetal head compression and require no intervention.
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Topics

Obstetric Complications

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