Effect of 1 week of oral hydration on the amniotic fluid index.

Objective: To evaluate the effect of long-term (1-week) oral hydration on amniotic fluid volume in women with an amniotic fluid index (AFI) < 10th percentile.

Study Design: This prospective, nonrandomized, interventional study was conducted on 30 women with AFI < 10th percentile. Study inclusion criteria were singleton pregnancy, well-established gestational age, intact membranes, no maternal complications (e.g., hypertension, cardiovascular disease, hyperthyroidism), no evidence of preeclampsia, no fetal structural malformations and no evidence of fetal distress. The women were instructed to drink at least 2L of water daily; their AFI was evaluated before and 1 week after the initiation of oral hydration. The study group was compared to a control group of 30 women matched for age and gestational age, with AFI > 10th and < 90th percentile.

Results: AFI increased from 8.1 +/- 0.73 (mean +/- SD) to 11.8 +/- 2.4 1 week later (P < .01) in 25 (83%) of the study subjects. The AFI was similar before and 1 week after oral hydration in all the controls.

Conclusion: Long-term maternal oral hydration seems to significantly increase the AFI in selected women with reduced fluid and possibly prevents oligohydramnios.