Maternal hydration therapy improves the quantity of amniotic fluid and the pregnancy outcome in third-trimester isolated oligohydramnios: a controlled randomized institutional trial.

OBJECTIVES: Amniotic fluid is important for the maintenance of fetal well-being; therefore, an amniotic fluid deficiency, ie, oligohydramnios, can have multiple impacts on the prognosis of the pregnancy. In some cases, there are no evident fetal or maternal causes, and the condition is called isolated oligohydramnios. The aim of our study was to validate maternal intravenous and oral hydration therapy as a means for improvement of isolated oligohydramnios in the third trimester of pregnancy.

METHODS: We conducted a prospective randomized controlled study on pregnancies complicated by idiopathic oligohydramnios (group A, 66 women) with a control group of women with normal pregnancies without oligohydramnios (group B, 71 women). Oligohydramnios was diagnosed using the amniotic fluid index (AFI; <5 cm). Sonographic examinations were performed with a convex 3.5-MHz probe. Group A underwent 6 days of intravenous infusion of 1500 mL of an isotonic solution per day. An AFI measurement, a nonstress test, and a fetal biophysical profile were performed at 0 and 7 days. Group A was randomized into subgroups A1 and A2. Subgroup A1 was prescribed home oral hydration therapy of 1500 mL/d and subgroup A2 2500 mL/d. We considered the AFI to compare the effectiveness of the therapy.

RESULTS: General features did not reveal any significant differences between the two groups. In group A, the mean AFI ± SD at recruitment was 39.68 ± 11.11 mm; in group B, it was 126.92 ± 10.59 mm (P < .001). In group A, the mean AFI at 7 days was 77.70 ± 15.03 mm; in group B, it was unchanged. In subgroup A1, the mean AFI at birth was 86.21 ± 16.89 mm; in subgroup A2, it was 112.45 ± 14.92 mm (P < .001).

CONCLUSIONS: Our data show that in pregnancies complicated by isolated oligohydramnios, hydration therapy significantly improves the quantity of amniotic fluid.