The nurse is administering terbutaline (Brethine) to a pregnant woman to prevent preterm labor. The nurse would assess for which adverse effect?

Choice A rationale Terbutaline is a β_2-adrenergic agonist, which primarily relaxes the smooth muscle of the uterus to suppress preterm labor. A common side effect is maternal hypotension due to vasodilation, rather than hypertension, as the drug stimulates β_2 receptors in the vascular smooth muscle, decreasing peripheral vascular resistance. The nurse should, therefore, monitor for a decrease in blood pressure, not an increase. Choice B rationale Terbutaline is a non-selective β-agonist, stimulating β_1 receptors in the heart in addition to the uterine β_2 receptors. Stimulation of β_1 receptors increases the heart rate and contractility, leading to maternal tachycardia (heart rate typically ≥ 120 beats/min is considered a serious adverse effect). This cardiovascular effect is a significant concern that the nurse must monitor closely for and report. Choice C rationale The β-agonist effect of terbutaline also crosses the placenta, potentially causing fetal tachycardia, not bradycardia, due to β_1 stimulation of the fetal heart. The drug's primary action on the uterus is relaxation, which improves uteroplacental perfusion, but the cardiac side effect is the concern, requiring fetal heart rate monitoring for signs of distress. Choice D rationale Terbutaline has numerous known adverse effects due to its β-adrenergic agonist properties. Common side effects include maternal and fetal tachycardia, palpitations, chest pain, tremors, headache, and potential hyperglycemia or hypokalemia. Stating there are no known adverse effects is scientifically incorrect, as pharmacologic agents inherently carry potential risks.