Intravenous fluid rate of 250 mL/h versus 125 mL/h in nulliparous women: A systematic review and meta-analysis of randomized controlled trials

Background: Evidence regarding the type and rate of intravenous (IV) fluid administration during labor is still inconclusive and the studies assessing the impact of IV fluids had mixed results.Objectives: To evaluate the effects of IV fluids at an infusion rate of 250 mL/h as compared with 125 mL/h on labor outcomes in nulliparous women.Search Strategy: We searched six databases for relevant studies through a search strategy containing the relevant keywords "IV hydration", "IV fluids", and "labor" from the inception of these databases to May 1, 2023, without any applied restrictions.Selection Criteria: Search results were imported to Covidence for screening of eligible articles for this review. Randomized controlled trials (RCTs) assessing the impact of IV fluids at 250 mL/h on the outcomes of labor in nulliparous women at term (>37 weeks) as compared with 125 mL/h were included only.Data Collection and Analysis: Data regarding the characteristics of included studies, participant's baseline characteristics, and concerned outcomes were collected in an Excel spreadsheet and all the concerned outcomes were pooled as risk ratios (RR) or mean difference (MD) with 95% confidence interval (CI) in the meta-analysis models using RevMan 5.4.Main results: Pooled data from 11 RCTs with 1815 patients showed that 250 mL/h infusion rate had a significant reduction in cesarean section rate (RR 0.70, 95% CI 0.56-0.88, P = 0.002), the first stage of labor duration (MD -46.97, 95% CI -81.79 to -12.14, P = 0.008), the second stage of labor duration (MD -2.69, 95% CI -4.34 to -1.05, P = 0.001), prolonged labor incidence (RR 0.72, 95% CI 0.58-0.89, P = 0.003), as compared with 125 mL/h. Also, the vaginal delivery rate (RR 1.07, 95% CI 1.02-1.12, P = 0.009) was higher with a 250 mL/h infusion rate.Conclusion: IV fluids at an infusion rate of 250 mL/h during labor in nulliparous women decreased the cesarean delivery rate, increased the vaginal delivery rate, shortened the first and second-stage labor duration, decreased the incidence of prolonged labor as compared with 125 mL/h. These findings suggest enhanced labor progression and a lower risk of labor complications with higher infusion rates. However, future research involving a more diverse population and exploring the potential benefits of combining IV infusion rates with other interventions, such as adding dextrose or less restrictive oral intake during labor, is needed.