What effect does terbutaline have on the fetus?

Terbutaline is a beta-agonist medication commonly used as a tocolytic agent to relax the uterus and inhibit premature contractions during pregnancy. When terbutaline is administered, it has a stimulatory effect on beta receptors, particularly beta-2 adrenergic receptors, which are located in various tissues including the smooth muscle of the uterus and the heart. This stimulation leads to an increased baseline fetal heart rate.

The increase in fetal heart rate occurs as a result of terbutaline's effects on the maternal and fetal cardiovascular systems. It acts to promote increased blood flow and oxygen delivery to the fetus, which can lead to an increase in the baseline fetal heart rate seen on monitoring.

In contrast, the other choices do not accurately reflect the pharmacological effects of terbutaline on fetal heart rate dynamics. It does not decrease the fetal heart rate nor typically lead to bradycardia, which would be a low heart rate; rather, it generally precipitates an increase in heart rate. Understanding these effects is crucial for monitoring fetal wellbeing during therapy with terbutaline, particularly in a clinical setting where the expected responses to the medication can guide further management decisions.