Increased Intravenous Fluid Intake and the Course of Labor in Nulliparous Women

Adequate hydration improves muscle performance during prolonged exercise, and this should apply to myometrial contractility during labor. In general, parturients receive intravenous fluid at a rate of 125 mL/hour, amounting to 3 L in 24 hours, but this rate is based on a resting patient not taking oral fluids and it does not always prevent clinical dehydration. This prospective, randomized, double-blind study compared the conventional regimen of 125 mL/hour (group 1) with 250 mL/hour of Ringer solution (group 2). Participants were 300 nulliparous women at term who had singleton pregnancies of 37 weeks or longer with a cephalic presentation. Labor began spontaneously in all cases. The 2 groups were matched for maternal and gestational ages, Bishop score, state of the membranes, birth weight, and infant gender. Women in group 1 received a mean of 810 mL of fluid, and women in group 2 1065 mL, a significant difference (P < .01). Both the first stage of labor and its total duration, but not the mean duration of the second stage, were significantly shorter in women in group 2 given the larger amount of intravenous fluid. Among women who delivered vaginally, labor lasting longer than 10 hours was significantly more frequent in group 1, and the same was the case for prolonged labor when defined as labor lasting longer than 15 hours. Significantly more women in group 1 received oxytocin to hasten the progress of labor. Ten women in group 1 and one woman in group 2 had operative delivery because labor failed to progress. Rates of vacuum extraction did not differ significantly in the 2 groups. Four newborn infants of mothers in group 1 but none in group 2 had a 5-minute Apgar score less than 7. No infant in either group was admitted to neonatal intensive care. Delivering twice as much intravenous fluid during labor as is ordinarily administered significantly shortened labor in this study of nulliparous women who spontaneously entered labor at term. This practice may lessen the risk of prolonged labor and also the need for oxytocin.