Why does potassium chloride 0.3%, sodium chloride 0.18% and glucose 4% infusion require special caution during labour when given with oxytocin?

The Baxter Healthcare Ltd potassium chloride 0.3%, sodium chloride 0.18% and glucose 4% infusion product requires special caution in pregnant women during labour, particularly with oxytocin, because of the risk of hyponatraemia.