The association of intrapartum IV fluid rates during labor with birth weight

Since discovering that intravenous (IV) fluid infusion rate of 250 mL/hr during labor decreases incidence of cesarean delivery and decreases time in labor when compared to infusion rate of 125 mL/hr, patients and midwives have expressed concern that increased fluid rates may lead to increased birth weights. Thus, our objectives were to determine the impact, if any, of increased IV fluid infusion rates on birth weight.

This was a meta-analysis of all randomized controlled trials (RCTs) of low-risk, nulliparous women with gestations ≥ 36 weeks comparing IV fluid rates of 125 vs. 250 mL/hr. We conducted a comprehensive literature search to identify studies published since the meta-analysis by Ehsanipoor et al. (2017) that assessed the impact of IV fluid rate on birth weight. For our analysis, we included the articles published since 2017 as well as articles from the original meta-analysis that included birth weight (6/7 studies).

Eight trials, with an overall low risk of bias, including 1727 women were analyzed. 913 were in the 125 ml/hr group and 876 were in the 250 ml/hr group. The vast majority of the included trials used Ringer's solution or normal saline. Overall, there was no significant difference in birth weights between the two treatment groups (mean difference -22.69 g; 95 % CI -75.52 to + 27.14).

We conclude that in addition to the previously demonstrated decreased incidence of cesarean delivery and length of labor demonstrated in Ehsanipoor et al. afforded by increased rate of IV fluid intake, there is no significant impact on birth weight.