Duration of the increase in amniotic fluid index (AFI) after acute maternal hydration.

The long-term effect of acute maternal hydration on amniotic fluid index (AFI) has not been previously studied. We evaluated the AFI of 25 pregnant women (ten women with normal AFI and 15 with decreased AFI) at 3, 24 and 48 h after maternal oral hydration with 2 l of water over 1 h. Post-hydration AFI at 3 h was significantly greater than pre-hydration AFI. However, AFI at 24 and 48 h were not significantly different from pre-hydration AFI. Maternal hydration increases AFI in women with normal and decreased amniotic fluid, but the increase in AFI lasts for less than 24 h.