A randomized controlled trial of the effect of increased intravenous hydration on the course of labor in nulliparous women.

OBJECTIVE: One variable that has the potential to affect the course of labor but has not been evaluated previously is the adequacy of maternal hydration. Typical orders provide for 125 mL of intravenous fluids per hour in patients taking limited oral fluids. Many such patients are clinically dehydrated. Physiologists have shown that increased fluids improve skeletal muscle performance in prolonged exercise. This study was designed to determine whether increased intravenous fluids affect the progress of labor.

STUDY DESIGN: Nulliparous women with uncomplicated singleton gestations at term, in spontaneous active labor with dilatation between 2 and 5 cm, and with a cephalic presentation were included. Patients who gave consent were randomly selected to receive either 125 mL or 250 mL of intravenous fluids per hour.

RESULTS: One hundred ninety-five patients were randomly selected, 94 to the 125-mL group and 101 to the 250-mL group. Prerandomization variables were well matched between the 2 groups. The mean volume of total intravenous fluids was significantly greater in the 250-mL group (2008 mL vs 2487 mL; P =.002), as was the mean hourly rate (152 mL/h in the 125-mL group vs 254 mL/h in the 250-mL group; P =.001). The frequency of labor lasting >12 hours was statistically higher in the 125-mL group (20/78 [26%] vs 12/91 [13%]; P =.047). In addition, there was a trend favoring longer mean duration of the first stage and total duration of labor in patients delivered vaginally in the 125-mL group, by 70 and 68 minutes, respectively (P =.06). There was a trend toward a lower frequency of oxytocin administration for inadequate labor progress in the higher fluid rate group (61 [65%] in the 125-mL group vs 51 [49%] in the 250-mL group; P =.06). Cesarean deliveries were more frequent in the 125-mL group (n = 16) than in the 250-mL group (n = 10) but did not reach statistical significance.

CONCLUSION: This study presents the novel finding that increasing fluid administration for nulliparous women in labor above rates commonly used is associated with a lower frequency of prolonged labor and possibly less need for oxytocin. Thus inadequate hydration in labor may be a factor contributing to dysfunctional labor and possibly cesarean delivery. Consideration of this factor in clinical management and in future studies considering variables that affect labor is warranted.