Which finding indicates that terbutaline has been effective in a patient receiving the medication?

The finding that indicates terbutaline has been effective is a decreased frequency of contractions. Terbutaline is a beta-agonist commonly used as a tocolytic agent to inhibit premature labor by relaxing the smooth muscles of the uterus. When terbutaline is effective, you would expect to see a reduction in the intensity or frequency of uterine contractions, which is its primary therapeutic effect.

In contrast, increased frequency of contractions would suggest that the medication is not achieving its desired effect. A decreased fetal heart rate could indicate fetal distress, which would not be related to the therapeutic effectiveness of terbutaline and may require immediate attention. Similarly, increased maternal blood pressure is not a desired outcome when administering terbutaline, as the medication is intended to relax the uterine muscles without adversely affecting maternal hemodynamics. Thus, the correct finding that demonstrates the effectiveness of terbutaline is indeed a decreased frequency of contractions.