Final answer:
A client in labor receiving an oxytocin infusion should be monitored for water intoxication, which is a risk due to oxytocin's antidiuretic effects and can cause dilutional hyponatremia.
Step-by-step explanation:
The client in labor receiving an oxytocin (Pitocin) infusion should be monitored for the adverse reaction of water intoxication. Oxytocin has antidiuretic effects, very similar to the antidiuretic hormone (ADH), which can lead to fluid retention and result in a dilutional hyponatremia, a condition where there is too much water in the body in relation to sodium. This is especially a concern with prolonged administration or high doses of oxytocin.