A nurse is caring for a client who is at 35 weeks of gestation and is receiving magnesium sulfate for treatment of preeclampsia.
Which of the following findings indicates that the medication is having the desired effect?

The nurse should further evaluate respiratory characteristics and muscle tone to determine if the newborn is experiencing a complication.

Rationale for correct answers
Respiratory characteristics are critical to assess because irregular and shallow breathing in a newborn can indicate neurological or respiratory dysfunction. Normal neonatal respiratory rate ranges from 30 to 60 breaths per minute with regular pattern; deviations may signal distress or central nervous system issues. Muscle tone evaluation is essential since increased tone with tremors suggests possible neurologic irritability or withdrawal. Normal newborn muscle tone should be moderate, neither hypotonic nor hypertonic, with symmetrical movement. These signs correlate with the high-pitched cry, tremors, and exaggerated reflexes noted, which may indicate neurological complications such as withdrawal syndrome or hypoxic-ischemic encephalopathy.

Rationale for incorrect answers
Heart rate (A) is important but was not reported abnormal; normal neonatal heart rate ranges from 120 to 160 beats per minute and the absence of murmurs suggests no cardiac compromise. Temperature (C) is less urgent as mucous membranes are moist and skin warm and dry, indicating stable thermoregulation; normal newborn temperature is 36.5–37.5°C. Feeding patterns (D) appear adequate with no difficulty reported, making this less immediately concerning.

Rationale for incorrect answers
Moro reflex (A) and Babinski reflex (B) are both present and exaggerated, which may be reactive but less specific for immediate concern than muscle tone abnormalities. Skin color (D) is normal without cyanosis or jaundice, reducing the likelihood of hypoxia or hemolytic issues.

Take home points

• Respiratory pattern irregularities in newborns may indicate neurological or respiratory dysfunction.
• Abnormal muscle tone and tremors are key signs of potential neurological complications.
• Normal heart rate, temperature, feeding, and skin color reduce likelihood of cardiac or systemic illness.
• Reflex exaggeration alone is less specific than muscle tone and respiratory changes for early complication detection.

Abruptio Placentae: Typically does not cause increased contraction frequency; contractions may be normal or decreased due to uterine irritation or pain.

Uterine Tachysystole: Characterized by more than 5 contractions in 10 minutes averaged over 30 minutes, indicating excessive contraction frequency, which can reduce uteroplacental perfusion.

Uterine Tone
Abruptio Placentae: The uterus often becomes firm, rigid, and tender due to bleeding and inflammation caused by premature placental separation, increasing baseline uterine tone.

Uterine Tachysystole: Uterine tone is elevated because contractions are prolonged and close together, causing the uterus to remain tense with insufficient relaxation.

Pain Report
Abruptio Placentae: Patients usually report sharp, severe abdominal or back pain due to the sudden placental detachment and uterine irritation.

Uterine Tachysystole: Pain may be present but is typically related to frequent contractions rather than sharp, localized pain.

FHR Pattern
Abruptio Placentae: Commonly causes fetal heart rate abnormalities like late decelerations, bradycardia, or absent variability due to fetal hypoxia from compromised placental perfusion.

Uterine Tachysystole: Can cause decreased fetal heart rate variability and late decelerations because frequent contractions reduce oxygen delivery during inadequate relaxation.