A randomized clinical trial comparing the effect of maternal intravenous hydration and placebo on the amniotic fluid index in oligohydramnios

Objective. To compare the treatment of acute intravenous hydration with placebo in term pregnant women manifesting oligohydramnios. Methods. All patients with oligohydramnios who met the inclusion criteria were offered participation in this randomized, double-blind, placebo-controlled study. After ruling out rupture of membranes and maternal and fetal complications, we recruited 44 women with third trimester singleton pregnancies having an amniotic fluid index (AFI) of less than 6. Patients were randomized into treatment or control groups. Patients in the treatment group received a continuous intravenous infusion of normal saline (NS) at a rate of 1000 mL/h for two hours. Patients in the placebo group received an intravenous infusion of NS at 10 mL/h for two hours. The AFI was re-assessed by the same sonographer one hour after the hydration was completed. Both the patient and the examiner were blinded to the study groups. Results. Maternal age, parity, gestational age, and birth weight were not significantly different between the two groups. The AFI increased significantly in both treatment (3.8 +/- 1.2 vs. 5.3 +/- 2.5, p < 0.05) and placebo (4 +/- 1.3 vs. 5.5 +/- 2.4, p < 0.05) groups. Moreover, the changes in AFI did not significantly differ between the treatment and the placebo groups (1.2 +/- 2.1 vs. 1.5 +/- 2.1, respectively; p > 0.05). Conclusions. There are statistically significant short-term increases in the AFI in patients with oligohydramnios whether the patients are treated with intravenous fluids or not. The short-term increase in AFI may reflect physiologic diurnal variations in the amniotic fluid.