What may cause fetal tachycardia without accompanying decelerations?

• A. Narcotics given to the woman in labor
• B. Fetal hypothyroidism
• C. Dehydration
• D. Maternal fever

Answer: (D)

Fetal tachycardia without decelerations is most commonly produced by maternal fever. When the mother has a fever during labor, the fetus is exposed to higher temperatures and inflammatory mediators, which raise the fetal metabolic rate and stimulate the sympathetic system, leading to a persistently elevated fetal heart rate. This pattern, driven by a systemic febrile response, typically lacks the periodic decelerations seen with hypoxia or uteroplacental insufficiency. The other options don’t fit as well: narcotics can affect fetal heart rate in other ways, often with changes in variability or potential depression rather than isolated tachycardia; fetal hypothyroidism tends to slow the heart rate; dehydration can impact perfusion but isn’t the classic trigger for tachycardia without decelerations.